Properties Editor: Grease Pencil and pinning fixes

The UI was trying to use screen_context.c for its poll and draw
functions. So the active object and active object data and active layer
was used in the UI, instead of the context one.

Besides, for the material, the wrong context path was used altogether
when the active object was a greasepencil.

This would lead to all sort of pinning problems:

* A Mesh panel is pinned, but the active object is a grease pencil, the
grease pencil panels would show.

* If a Grease Pencil (data) panel is pinned, but the active object is not
the one pinned, nothing would show.

* Material panels and pinning were totally broken, showing the material
context for pinned mesh data panels even.

I also sanitized the name of the panels, their inheritance and poll
functions.

Reviewers: antoniov, brecht

Subscribers: billrey

Differential Revision: https://developer.blender.org/D4470

4 files changed, 151 insertions, 196 deletions

diff --git a/release/scripts/startup/bl_ui/properties_data_gpencil.py b/release/scripts/startup/bl_ui/properties_data_gpencil.py
index a5e526ed670..c6626b555fb 100644
--- a/release/scripts/startup/bl_ui/properties_data_gpencil.py
+++ b/release/scripts/startup/bl_ui/properties_data_gpencil.py
@@ -35,7 +35,7 @@ class DataButtonsPanel:
 
     @classmethod
     def poll(cls, context):
-        return context.gpencil_data
+        return context.gpencil
 
 
 class ObjectButtonsPanel:
@@ -45,7 +45,8 @@ class ObjectButtonsPanel:
 
     @classmethod
     def poll(cls, context):
-        return context.object and context.object.type == 'GPENCIL'
+        ob = context.object
+        return ob and ob.type == 'GPENCIL'
 
 
 class LayerDataButtonsPanel:
@@ -55,24 +56,28 @@ class LayerDataButtonsPanel:
 
     @classmethod
     def poll(cls, context):
-        return (context.gpencil_data and
-                context.active_gpencil_layer)
+        gpencil = context.gpencil
+        return gpencil and gpencil.layers.active
 
 
 ###############################
 # GP Object Properties Panels and Helper Classes
 
-class DATA_PT_gpencil(DataButtonsPanel, Panel):
+class DATA_PT_context_gpencil(DataButtonsPanel, Panel):
     bl_label = ""
     bl_options = {'HIDE_HEADER'}
 
     def draw(self, context):
         layout = self.layout
 
-        # Grease Pencil data selector
-        gpd_owner = context.gpencil_data_owner
+        ob = context.object
+        gpencil = context.gpencil
+        space = context.space_data
 
-        layout.template_ID(gpd_owner, "data")
+        if ob:
+            layout.template_ID(ob, "data")
+        else:
+            layout.template_ID(space, "pin_id")
 
 
 class GPENCIL_MT_layer_specials(Menu):
@@ -80,7 +85,7 @@ class GPENCIL_MT_layer_specials(Menu):
 
     def draw(self, context):
         layout = self.layout
-        gpd = context.gpencil_data
+        gpd = context.gpencil
 
         layout.operator("gpencil.layer_duplicate", icon='ADD')  # XXX: needs a dedicated icon
 
@@ -103,23 +108,15 @@ class GPENCIL_MT_layer_specials(Menu):
         layout.menu("VIEW3D_MT_gpencil_copy_layer")
 
 
-class DATA_PT_gpencil_datapanel(Panel):
-    bl_space_type = 'PROPERTIES'
-    bl_region_type = 'WINDOW'
-    bl_context = "data"
+class DATA_PT_gpencil_layers(DataButtonsPanel, Panel):
     bl_label = "Layers"
 
-    @classmethod
-    def poll(cls, context):
-        return context.gpencil_data
-
-    @staticmethod
     def draw(self, context):
         layout = self.layout
         #layout.use_property_split = True
         layout.use_property_decorate = False
 
-        gpd = context.gpencil_data
+        gpd = context.gpencil
 
         # Grease Pencil data...
         if (gpd is None) or (not gpd.layers):
@@ -136,7 +133,8 @@ class DATA_PT_gpencil_datapanel(Panel):
         col.template_list("GPENCIL_UL_layer", "", gpd, "layers", gpd.layers, "active_index",
                           rows=layer_rows, sort_reverse=True, sort_lock=True)
 
-        gpl = context.active_gpencil_layer
+        gpl = gpd.layers.active
+
         if gpl:
             srow = col.row(align=True)
             srow.prop(gpl, "blend_mode", text="Blend")
@@ -172,12 +170,9 @@ class DATA_PT_gpencil_datapanel(Panel):
                 sub.operator("gpencil.layer_isolate", icon='RESTRICT_VIEW_ON', text="").affect_visibility = True
 
 
-class DATA_PT_gpencil_layer_optionpanel(LayerDataButtonsPanel, Panel):
-    bl_space_type = 'PROPERTIES'
-    bl_region_type = 'WINDOW'
-    bl_context = "data"
+class DATA_PT_gpencil_layer_adjustments(LayerDataButtonsPanel, Panel):
     bl_label = "Adjustments"
-    bl_parent_id = 'DATA_PT_gpencil_datapanel'
+    bl_parent_id = 'DATA_PT_gpencil_layers'
     bl_options = {'DEFAULT_CLOSED'}
 
     def draw(self, context):
@@ -185,7 +180,8 @@ class DATA_PT_gpencil_layer_optionpanel(LayerDataButtonsPanel, Panel):
         layout.use_property_split = True
         scene = context.scene
 
-        gpl = context.active_gpencil_layer
+        gpd = context.gpencil
+        gpl = gpd.layers.active
         layout.active = not gpl.lock
 
         # Layer options
@@ -209,12 +205,9 @@ class DATA_PT_gpencil_layer_optionpanel(LayerDataButtonsPanel, Panel):
         col.prop(gpl, "lock_material")
 
 
-class DATA_PT_gpencil_parentpanel(LayerDataButtonsPanel, Panel):
-    bl_space_type = 'PROPERTIES'
-    bl_region_type = 'WINDOW'
-    bl_context = "data"
+class DATA_PT_gpencil_layer_relations(LayerDataButtonsPanel, Panel):
     bl_label = "Relations"
-    bl_parent_id = 'DATA_PT_gpencil_datapanel'
+    bl_parent_id = 'DATA_PT_gpencil_layers'
     bl_options = {'DEFAULT_CLOSED'}
 
     def draw(self, context):
@@ -222,7 +215,9 @@ class DATA_PT_gpencil_parentpanel(LayerDataButtonsPanel, Panel):
         layout.use_property_split = True
         layout.use_property_decorate = False
 
-        gpl = context.active_gpencil_layer
+        gpd = context.gpencil
+        gpl = gpd.layers.active
+
         col = layout.column()
         col.active = not gpl.lock
         col.prop(gpl, "parent")
@@ -233,19 +228,12 @@ class DATA_PT_gpencil_parentpanel(LayerDataButtonsPanel, Panel):
             col.prop_search(gpl, "parent_bone", parent.data, "bones", text="Bone")
 
 
-class DATA_PT_gpencil_onionpanel(Panel):
-    bl_space_type = 'PROPERTIES'
-    bl_region_type = 'WINDOW'
-    bl_context = "data"
+class DATA_PT_gpencil_onion_skinning(DataButtonsPanel, Panel):
     bl_label = "Onion Skinning"
     bl_options = {'DEFAULT_CLOSED'}
 
-    @classmethod
-    def poll(cls, context):
-        return bool(context.active_gpencil_layer)
-
     def draw(self, context):
-        gpd = context.gpencil_data
+        gpd = context.gpencil
 
         layout = self.layout
         layout.use_property_split = True
@@ -268,21 +256,18 @@ class DATA_PT_gpencil_onionpanel(Panel):
             col.prop(gpd, "ghost_after_range", text="Keyframes After")
 
 
-class DATA_PT_gpencil_onionpanel_custom_colors(Panel):
-    bl_space_type = 'PROPERTIES'
-    bl_region_type = 'WINDOW'
-    bl_context = "data"
-    bl_parent_id = "DATA_PT_gpencil_onionpanel"
+class DATA_PT_gpencil_onion_skinning_custom_colors(DataButtonsPanel, Panel):
+    bl_parent_id = "DATA_PT_gpencil_onion_skinning"
     bl_label = "Custom Colors"
     bl_options = {'DEFAULT_CLOSED'}
 
     def draw_header(self, context):
-        gpd = context.gpencil_data
+        gpd = context.gpencil
 
         self.layout.prop(gpd, "use_ghost_custom_colors", text="")
 
     def draw(self, context):
-        gpd = context.gpencil_data
+        gpd = context.gpencil
 
         layout = self.layout
         layout.use_property_split = True
@@ -292,16 +277,13 @@ class DATA_PT_gpencil_onionpanel_custom_colors(Panel):
         layout.prop(gpd, "after_color", text="After")
 
 
-class DATA_PT_gpencil_onionpanel_display(Panel):
-    bl_space_type = 'PROPERTIES'
-    bl_region_type = 'WINDOW'
-    bl_context = "data"
-    bl_parent_id = "DATA_PT_gpencil_onionpanel"
+class DATA_PT_gpencil_onion_skinning_display(DataButtonsPanel, Panel):
+    bl_parent_id = "DATA_PT_gpencil_onion_skinning"
     bl_label = "Display"
     bl_options = {'DEFAULT_CLOSED'}
 
     def draw(self, context):
-        gpd = context.gpencil_data
+        gpd = context.gpencil
 
         layout = self.layout
         layout.use_property_split = True
@@ -354,10 +336,7 @@ class GPENCIL_UL_vgroups(UIList):
             layout.label(text="", icon_value=icon)
 
 
-class DATA_PT_gpencil_vertexpanel(ObjectButtonsPanel, Panel):
-    bl_space_type = 'PROPERTIES'
-    bl_region_type = 'WINDOW'
-    bl_context = "data"
+class DATA_PT_gpencil_vertex_groups(ObjectButtonsPanel, Panel):
     bl_label = "Vertex Groups"
     bl_options = {'DEFAULT_CLOSED'}
 
@@ -402,12 +381,13 @@ class DATA_PT_gpencil_strokes(DataButtonsPanel, Panel):
         layout.use_property_decorate = False
 
         ob = context.object
-
-        gpd = context.gpencil_data
+        gpd = context.gpencil
 
         col = layout.column(align=True)
         col.prop(gpd, "stroke_depth_order")
-        col.enabled = not ob.show_in_front
+
+        if ob:
+            col.enabled = not ob.show_in_front
 
         col = layout.column(align=True)
         col.prop(gpd, "stroke_thickness_space")
@@ -419,7 +399,7 @@ class DATA_PT_gpencil_strokes(DataButtonsPanel, Panel):
         layout.prop(gpd, "use_adaptive_uv", text="Adaptive UVs")
 
 
-class DATA_PT_gpencil_display(ObjectButtonsPanel, Panel):
+class DATA_PT_gpencil_display(DataButtonsPanel, Panel):
     bl_label = "Viewport Display"
     bl_options = {'DEFAULT_CLOSED'}
 
@@ -428,10 +408,8 @@ class DATA_PT_gpencil_display(ObjectButtonsPanel, Panel):
         layout.use_property_split = True
         layout.use_property_decorate = False
 
-        ob = context.object
-
-        gpd = context.gpencil_data
-        gpl = context.active_gpencil_layer
+        gpd = context.gpencil
+        gpl = gpd.layers.active
 
         layout.prop(gpd, "edit_line_color", text="Edit Line Color")
         if gpl:
@@ -447,7 +425,7 @@ class DATA_PT_gpencil_canvas(DataButtonsPanel, Panel):
         layout = self.layout
         layout.use_property_split = True
         layout.use_property_decorate = False
-        gpd = context.gpencil_data
+        gpd = context.gpencil
         grid = gpd.grid
 
         row = layout.row(align=True)
@@ -468,14 +446,14 @@ class DATA_PT_custom_props_gpencil(DataButtonsPanel, PropertyPanel, Panel):
 
 
 classes = (
-    DATA_PT_gpencil,
-    DATA_PT_gpencil_datapanel,
-    DATA_PT_gpencil_onionpanel,
-    DATA_PT_gpencil_onionpanel_custom_colors,
-    DATA_PT_gpencil_onionpanel_display,
-    DATA_PT_gpencil_layer_optionpanel,
-    DATA_PT_gpencil_parentpanel,
-    DATA_PT_gpencil_vertexpanel,
+    DATA_PT_context_gpencil,
+    DATA_PT_gpencil_layers,
+    DATA_PT_gpencil_onion_skinning,
+    DATA_PT_gpencil_onion_skinning_custom_colors,
+    DATA_PT_gpencil_onion_skinning_display,
+    DATA_PT_gpencil_layer_adjustments,
+    DATA_PT_gpencil_layer_relations,
+    DATA_PT_gpencil_vertex_groups,
     DATA_PT_gpencil_strokes,
     DATA_PT_gpencil_display,
     DATA_PT_gpencil_canvas,
diff --git a/release/scripts/startup/bl_ui/properties_grease_pencil_common.py b/release/scripts/startup/bl_ui/properties_grease_pencil_common.py
index 82677192590..d65d494630a 100644
--- a/release/scripts/startup/bl_ui/properties_grease_pencil_common.py
+++ b/release/scripts/startup/bl_ui/properties_grease_pencil_common.py
@@ -860,65 +860,70 @@ class GreasePencilMaterialsPanel:
     @classmethod
     def poll(cls, context):
         ob = context.object
-        return ob and ob.type == 'GPENCIL'
+        ma = context.material
+        return (ob and ob.type == 'GPENCIL') or (ma and ma.grease_pencil)
 
     @staticmethod
     def draw(self, context):
         layout = self.layout
         show_full_ui = (self.bl_space_type == 'PROPERTIES')
 
-        gpd = context.gpencil_data
-
         ob = context.object
-
-        is_sortable = len(ob.material_slots) > 1
-        rows = 7
+        gpd = context.gpencil
+        space = context.space_data
 
         row = layout.row()
 
-        row.template_list("GPENCIL_UL_matslots", "", ob, "material_slots", ob, "active_material_index", rows=rows)
+        if ob:
+            is_sortable = len(ob.material_slots) > 1
+            rows = 7
 
-        col = row.column(align=True)
-        if show_full_ui:
-            col.operator("object.material_slot_add", icon='ADD', text="")
-            col.operator("object.material_slot_remove", icon='REMOVE', text="")
+            row.template_list("GPENCIL_UL_matslots", "", ob, "material_slots", ob, "active_material_index", rows=rows)
 
-        col.menu("GPENCIL_MT_color_specials", icon='DOWNARROW_HLT', text="")
+            col = row.column(align=True)
+            if show_full_ui:
+                col.operator("object.material_slot_add", icon='ADD', text="")
+                col.operator("object.material_slot_remove", icon='REMOVE', text="")
 
-        if is_sortable:
-            col.separator()
+            col.menu("GPENCIL_MT_color_specials", icon='DOWNARROW_HLT', text="")
 
-            col.operator("object.material_slot_move", icon='TRIA_UP', text="").direction = 'UP'
-            col.operator("object.material_slot_move", icon='TRIA_DOWN', text="").direction = 'DOWN'
+            if is_sortable:
+                col.separator()
 
-            col.separator()
+                col.operator("object.material_slot_move", icon='TRIA_UP', text="").direction = 'UP'
+                col.operator("object.material_slot_move", icon='TRIA_DOWN', text="").direction = 'DOWN'
 
-            sub = col.column(align=True)
-            sub.operator("gpencil.color_isolate", icon='LOCKED', text="").affect_visibility = False
-            sub.operator("gpencil.color_isolate", icon='RESTRICT_VIEW_ON', text="").affect_visibility = True
+                col.separator()
+
+                sub = col.column(align=True)
+                sub.operator("gpencil.color_isolate", icon='LOCKED', text="").affect_visibility = False
+                sub.operator("gpencil.color_isolate", icon='RESTRICT_VIEW_ON', text="").affect_visibility = True
 
-        if show_full_ui:
-            row = layout.row()
+            if show_full_ui:
+                row = layout.row()
 
-            row.template_ID(ob, "active_material", new="material.new", live_icon=True)
+                row.template_ID(ob, "active_material", new="material.new", live_icon=True)
 
-            slot = context.material_slot
-            if slot:
-                icon_link = 'MESH_DATA' if slot.link == 'DATA' else 'OBJECT_DATA'
-                row.prop(slot, "link", icon=icon_link, icon_only=True)
+                slot = context.material_slot
+                if slot:
+                    icon_link = 'MESH_DATA' if slot.link == 'DATA' else 'OBJECT_DATA'
+                    row.prop(slot, "link", icon=icon_link, icon_only=True)
 
-            if gpd.use_stroke_edit_mode:
-                row = layout.row(align=True)
-                row.operator("gpencil.stroke_change_color", text="Assign")
-                row.operator("gpencil.color_select", text="Select").deselect = False
-                row.operator("gpencil.color_select", text="Deselect").deselect = True
+                if gpd and gpd.use_stroke_edit_mode:
+                    row = layout.row(align=True)
+                    row.operator("gpencil.stroke_change_color", text="Assign")
+                    row.operator("gpencil.color_select", text="Select").deselect = False
+                    row.operator("gpencil.color_select", text="Deselect").deselect = True
+
+        else:
+            row.template_ID(space, "pin_id")
 
 
 class GPENCIL_UL_layer(UIList):
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname, index):
         # assert(isinstance(item, bpy.types.GPencilLayer)
         gpl = item
-        gpd = context.gpencil_data
+        gpd = context.gpencil
 
         if self.layout_type in {'DEFAULT', 'COMPACT'}:
             if gpl.lock:
diff --git a/release/scripts/startup/bl_ui/properties_material.py b/release/scripts/startup/bl_ui/properties_material.py
index 8d7e7ac266d..07c94c90738 100644
--- a/release/scripts/startup/bl_ui/properties_material.py
+++ b/release/scripts/startup/bl_ui/properties_material.py
@@ -60,7 +60,8 @@ class MaterialButtonsPanel:
 
     @classmethod
     def poll(cls, context):
-        return context.material and (context.engine in cls.COMPAT_ENGINES)
+        mat = context.material
+        return mat and (context.engine in cls.COMPAT_ENGINES) and not mat.grease_pencil
 
 
 class MATERIAL_PT_preview(MaterialButtonsPanel, Panel):
@@ -86,11 +87,8 @@ class EEVEE_MATERIAL_PT_context_material(MaterialButtonsPanel, Panel):
 
     @classmethod
     def poll(cls, context):
-        if context.active_object and context.active_object.type == 'GPENCIL':
-            return False
-        else:
-            engine = context.engine
-            return (context.material or context.object) and (engine in cls.COMPAT_ENGINES)
+        mat = context.material
+        return (context.object or mat) and (context.engine in cls.COMPAT_ENGINES) and not mat.grease_pencil
 
     def draw(self, context):
         layout = self.layout
@@ -161,11 +159,6 @@ class EEVEE_MATERIAL_PT_surface(MaterialButtonsPanel, Panel):
     bl_context = "material"
     COMPAT_ENGINES = {'BLENDER_EEVEE'}
 
-    @classmethod
-    def poll(cls, context):
-        engine = context.engine
-        return context.material and (engine in cls.COMPAT_ENGINES)
-
     def draw(self, context):
         layout = self.layout
 
@@ -194,7 +187,7 @@ class EEVEE_MATERIAL_PT_volume(MaterialButtonsPanel, Panel):
     def poll(cls, context):
         engine = context.engine
         mat = context.material
-        return mat and mat.use_nodes and (engine in cls.COMPAT_ENGINES)
+        return mat and mat.use_nodes and (engine in cls.COMPAT_ENGINES) and not mat.grease_pencil
 
     def draw(self, context):
         layout = self.layout
@@ -209,11 +202,6 @@ class EEVEE_MATERIAL_PT_settings(MaterialButtonsPanel, Panel):
     bl_context = "material"
     COMPAT_ENGINES = {'BLENDER_EEVEE'}
 
-    @classmethod
-    def poll(cls, context):
-        engine = context.engine
-        return context.material and (engine in cls.COMPAT_ENGINES)
-
     @staticmethod
     def draw_shared(self, mat):
         layout = self.layout
@@ -247,7 +235,8 @@ class MATERIAL_PT_viewport(MaterialButtonsPanel, Panel):
 
     @classmethod
     def poll(cls, context):
-        return context.material
+        mat = context.material
+        return mat and not mat.grease_pencil
 
     @staticmethod
     def draw_shared(self, mat):
diff --git a/release/scripts/startup/bl_ui/properties_material_gpencil.py b/release/scripts/startup/bl_ui/properties_material_gpencil.py
index 282f8d77515..c8691d15cc4 100644
--- a/release/scripts/startup/bl_ui/properties_material_gpencil.py
+++ b/release/scripts/startup/bl_ui/properties_material_gpencil.py
@@ -81,10 +81,8 @@ class GPMaterialButtonsPanel:
 
     @classmethod
     def poll(cls, context):
-        ob = context.object
-        return (ob and ob.type == 'GPENCIL' and
-                ob.active_material and
-                ob.active_material.grease_pencil)
+        ma = context.material
+        return ma and ma.grease_pencil
 
 
 class MATERIAL_PT_gpencil_slots(GreasePencilMaterialsPanel, Panel):
@@ -99,18 +97,6 @@ class MATERIAL_PT_gpencil_slots(GreasePencilMaterialsPanel, Panel):
 class MATERIAL_PT_gpencil_surface(GPMaterialButtonsPanel, Panel):
     bl_label = "Surface"
 
-    @classmethod
-    def poll(cls, context):
-        ob = context.object
-        if not (ob and ob.type == 'GPENCIL'):
-            return False
-
-        ma = ob.active_material
-        if not (ma and ma.grease_pencil):
-            return False
-
-        return True
-
     def draw_header_preset(self, context):
         MATERIAL_PT_gpencil_material_presets.draw_panel_header(self.layout)
 
@@ -125,7 +111,7 @@ class MATERIAL_PT_gpencil_strokecolor(GPMaterialButtonsPanel, Panel):
     bl_parent_id = 'MATERIAL_PT_gpencil_surface'
 
     def draw_header(self, context):
-        ma = context.object.active_material
+        ma = context.material
         if ma is not None and ma.grease_pencil is not None:
             gpcolor = ma.grease_pencil
             self.layout.prop(gpcolor, "show_stroke", text="")
@@ -135,7 +121,7 @@ class MATERIAL_PT_gpencil_strokecolor(GPMaterialButtonsPanel, Panel):
         layout = self.layout
         layout.use_property_split = True
 
-        ma = context.object.active_material
+        ma = context.material
         if ma is not None and ma.grease_pencil is not None:
             gpcolor = ma.grease_pencil
 
@@ -163,73 +149,71 @@ class MATERIAL_PT_gpencil_fillcolor(GPMaterialButtonsPanel, Panel):
     bl_parent_id = 'MATERIAL_PT_gpencil_surface'
 
     def draw_header(self, context):
-        ma = context.object.active_material
-        if ma is not None and ma.grease_pencil is not None:
-            gpcolor = ma.grease_pencil
-            self.layout.prop(gpcolor, "show_fill", text="")
+        ma = context.material
+        gpcolor = ma.grease_pencil
+        self.layout.prop(gpcolor, "show_fill", text="")
 
     @staticmethod
     def draw(self, context):
         layout = self.layout
         layout.use_property_split = True
 
-        ma = context.object.active_material
-        if ma is not None and ma.grease_pencil:
-            gpcolor = ma.grease_pencil
+        ma = context.material
+        gpcolor = ma.grease_pencil
 
-            # color settings
-            col = layout.column()
-            col.active = not gpcolor.lock
-            col.prop(gpcolor, "fill_style", text="Style")
+        # color settings
+        col = layout.column()
+        col.active = not gpcolor.lock
+        col.prop(gpcolor, "fill_style", text="Style")
 
-            if gpcolor.fill_style == 'GRADIENT':
-                col.prop(gpcolor, "gradient_type")
+        if gpcolor.fill_style == 'GRADIENT':
+            col.prop(gpcolor, "gradient_type")
 
-            if gpcolor.fill_style != 'TEXTURE':
-                col.prop(gpcolor, "fill_color", text="Color")
+        if gpcolor.fill_style != 'TEXTURE':
+            col.prop(gpcolor, "fill_color", text="Color")
 
-                if gpcolor.fill_style in {'GRADIENT', 'CHESSBOARD'}:
-                    col.prop(gpcolor, "mix_color", text="Secondary Color")
+            if gpcolor.fill_style in {'GRADIENT', 'CHESSBOARD'}:
+                col.prop(gpcolor, "mix_color", text="Secondary Color")
 
-                if gpcolor.fill_style == 'GRADIENT':
-                    col.prop(gpcolor, "mix_factor", text="Mix Factor", slider=True)
+            if gpcolor.fill_style == 'GRADIENT':
+                col.prop(gpcolor, "mix_factor", text="Mix Factor", slider=True)
 
-                if gpcolor.fill_style in {'GRADIENT', 'CHESSBOARD'}:
-                    col.prop(gpcolor, "flip", text="Flip Colors")
+            if gpcolor.fill_style in {'GRADIENT', 'CHESSBOARD'}:
+                col.prop(gpcolor, "flip", text="Flip Colors")
 
-                    col.prop(gpcolor, "pattern_shift", text="Location")
-                    col.prop(gpcolor, "pattern_scale", text="Scale")
+                col.prop(gpcolor, "pattern_shift", text="Location")
+                col.prop(gpcolor, "pattern_scale", text="Scale")
 
-                if gpcolor.gradient_type == 'RADIAL' and gpcolor.fill_style not in {'SOLID', 'CHESSBOARD'}:
-                    col.prop(gpcolor, "pattern_radius", text="Radius")
-                else:
-                    if gpcolor.fill_style != 'SOLID':
-                        col.prop(gpcolor, "pattern_angle", text="Angle")
+            if gpcolor.gradient_type == 'RADIAL' and gpcolor.fill_style not in {'SOLID', 'CHESSBOARD'}:
+                col.prop(gpcolor, "pattern_radius", text="Radius")
+            else:
+                if gpcolor.fill_style != 'SOLID':
+                    col.prop(gpcolor, "pattern_angle", text="Angle")
 
-                if gpcolor.fill_style == 'CHESSBOARD':
-                    col.prop(gpcolor, "pattern_gridsize", text="Box Size")
+            if gpcolor.fill_style == 'CHESSBOARD':
+                col.prop(gpcolor, "pattern_gridsize", text="Box Size")
 
-            # Texture
-            if gpcolor.fill_style == 'TEXTURE' or (gpcolor.texture_mix is True and gpcolor.fill_style == 'SOLID'):
-                col.template_ID(gpcolor, "fill_image", open="image.open")
+        # Texture
+        if gpcolor.fill_style == 'TEXTURE' or (gpcolor.texture_mix is True and gpcolor.fill_style == 'SOLID'):
+            col.template_ID(gpcolor, "fill_image", open="image.open")
 
-                if gpcolor.fill_style == 'TEXTURE':
-                    col.prop(gpcolor, "use_fill_pattern", text="Use As Pattern")
-                    if gpcolor.use_fill_pattern is True:
-                        col.prop(gpcolor, "fill_color", text="Color")
+            if gpcolor.fill_style == 'TEXTURE':
+                col.prop(gpcolor, "use_fill_pattern", text="Use As Pattern")
+                if gpcolor.use_fill_pattern is True:
+                    col.prop(gpcolor, "fill_color", text="Color")
 
-                col.prop(gpcolor, "texture_offset", text="Offset")
-                col.prop(gpcolor, "texture_scale", text="Scale")
-                col.prop(gpcolor, "texture_angle")
-                col.prop(gpcolor, "texture_opacity")
-                col.prop(gpcolor, "texture_clamp", text="Clip Image")
+            col.prop(gpcolor, "texture_offset", text="Offset")
+            col.prop(gpcolor, "texture_scale", text="Scale")
+            col.prop(gpcolor, "texture_angle")
+            col.prop(gpcolor, "texture_opacity")
+            col.prop(gpcolor, "texture_clamp", text="Clip Image")
 
-                if gpcolor.use_fill_pattern is False:
-                    col.prop(gpcolor, "texture_mix", text="Mix With Color")
+            if gpcolor.use_fill_pattern is False:
+                col.prop(gpcolor, "texture_mix", text="Mix With Color")
 
-                    if gpcolor.texture_mix is True:
-                        col.prop(gpcolor, "fill_color", text="Mix Color")
-                        col.prop(gpcolor, "mix_factor", text="Mix Factor", slider=True)
+                if gpcolor.texture_mix is True:
+                    col.prop(gpcolor, "fill_color", text="Mix Color")
+                    col.prop(gpcolor, "mix_factor", text="Mix Factor", slider=True)
 
 
 class MATERIAL_PT_gpencil_preview(GPMaterialButtonsPanel, Panel):
@@ -238,7 +222,7 @@ class MATERIAL_PT_gpencil_preview(GPMaterialButtonsPanel, Panel):
     bl_options = {'DEFAULT_CLOSED'}
 
     def draw(self, context):
-        ma = context.object.active_material
+        ma = context.material
         self.layout.label(text=ma.name)
         self.layout.template_preview(ma)
 
@@ -258,10 +242,9 @@ class MATERIAL_PT_gpencil_options(GPMaterialButtonsPanel, Panel):
         layout = self.layout
         layout.use_property_split = True
 
-        ma = context.object.active_material
-        if ma is not None and ma.grease_pencil is not None:
-            gpcolor = ma.grease_pencil
-            layout.prop(gpcolor, "pass_index")
+        ma = context.material
+        gpcolor = ma.grease_pencil
+        layout.prop(gpcolor, "pass_index")
 
 
 class MATERIAL_PT_gpencil_material_presets(PresetMenu):