UI: Grease Pencil Modifier Drag and Drop, Layout Changes

This patch implements the list panel system D7490 for grease pencil
modifiers. It also moves their drawing to a callback in
GpencilModifierTypeInfo in line with the extensible architecture
refactoring goal T75724.

This also adds the "set_error" function for grease pencil modifiers,
which hadn't been copied from mesh modifiers yet.

The implementation is basically exactly the same as for the modifier
patch (9b099c86123fc82).

Thanks to Matias Mendiola (mendio) for providing mockups for many
of the layout changes.

Differential Revision: https://developer.blender.org/D7978

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/makesdna/DNA_gpencil_modifier_types.h b/source/blender/makesdna/DNA_gpencil_modifier_types.h
index 674999ab465..5d35db1a960 100644
--- a/source/blender/makesdna/DNA_gpencil_modifier_types.h
+++ b/source/blender/makesdna/DNA_gpencil_modifier_types.h
@@ -58,7 +58,7 @@ typedef enum GpencilModifierMode {
   eGpencilModifierMode_Realtime = (1 << 0),
   eGpencilModifierMode_Render = (1 << 1),
   eGpencilModifierMode_Editmode = (1 << 2),
-  eGpencilModifierMode_Expanded = (1 << 3),
+  eGpencilModifierMode_Expanded_DEPRECATED = (1 << 3),
 } GpencilModifierMode;
 
 typedef enum {
@@ -72,7 +72,7 @@ typedef struct GpencilModifierData {
   int type, mode;
   int stackindex;
   short flag;
-  short _pad;
+  short ui_expand_flag;
   /** MAX_NAME. */
   char name[64];