Asset Browser: Move Asset Library selector to navigation bar

The menu to select the active Asset Library is now in the left bar (so called
"Source List", although I'd prefer "Navigation-Bar").

This has some benefits:
* All Asset Library navigation is in the left sidebar now, giving nice grouping
  and a top-to-bottom & left-to-right flow of the layout. The header is focused
  on view set-up now.
* Catalogs are stored inside the asset library. Makes sense to have them right
  under that.
* Less content in the header allows for less wide Asset Browsers without
  extensive scrolling.
* This location gives more space to add options or operators for Asset
  Libraries.

Main downside I see is that the side-bar needs to be opened to change
libraries, which takes quite some space. In practice there shouldn't be need to
do this often though.

3 files changed, 17 insertions, 7 deletions

diff --git a/release/scripts/startup/bl_ui/space_filebrowser.py b/release/scripts/startup/bl_ui/space_filebrowser.py
index 5dd8c69f3d5..f54a2446c7e 100644
--- a/release/scripts/startup/bl_ui/space_filebrowser.py
+++ b/release/scripts/startup/bl_ui/space_filebrowser.py
@@ -36,12 +36,6 @@ class FILEBROWSER_HT_header(Header):
         space_data = context.space_data
         params = space_data.params
 
-        row = layout.row(align=True)
-        row.prop(params, "asset_library_ref", text="")
-        # External libraries don't auto-refresh, add refresh button.
-        if params.asset_library_ref != 'LOCAL':
-            row.operator("file.refresh", text="", icon='FILE_REFRESH')
-
         layout.separator_spacer()
 
         layout.prop(params, "import_type", text="")
diff --git a/source/blender/editors/space_file/asset_catalog_tree_view.cc b/source/blender/editors/space_file/asset_catalog_tree_view.cc
index 84bfa58be85..28d64cfca60 100644
--- a/source/blender/editors/space_file/asset_catalog_tree_view.cc
+++ b/source/blender/editors/space_file/asset_catalog_tree_view.cc
@@ -479,6 +479,8 @@ void file_create_asset_catalog_tree_view_in_layout(::AssetLibrary *asset_library
 {
   uiBlock *block = uiLayoutGetBlock(layout);
 
+  UI_block_layout_set_current(block, layout);
+
   ui::AbstractTreeView *tree_view = UI_block_add_view(
       *block,
       "asset catalog tree view",
diff --git a/source/blender/editors/space_file/file_panels.c b/source/blender/editors/space_file/file_panels.c
index b530f1d0aa7..51d0581d6a4 100644
--- a/source/blender/editors/space_file/file_panels.c
+++ b/source/blender/editors/space_file/file_panels.c
@@ -232,13 +232,27 @@ void file_execute_region_panels_register(ARegionType *art)
 
 static void file_panel_asset_catalog_buttons_draw(const bContext *C, Panel *panel)
 {
+  bScreen *screen = CTX_wm_screen(C);
   SpaceFile *sfile = CTX_wm_space_file(C);
   /* May be null if the library wasn't loaded yet. */
   struct AssetLibrary *asset_library = filelist_asset_library(sfile->files);
   FileAssetSelectParams *params = ED_fileselect_get_asset_params(sfile);
   BLI_assert(params != NULL);
 
-  file_create_asset_catalog_tree_view_in_layout(asset_library, panel->layout, sfile, params);
+  uiLayout *col = uiLayoutColumn(panel->layout, false);
+  uiLayout *row = uiLayoutRow(col, true);
+
+  PointerRNA params_ptr;
+  RNA_pointer_create(&screen->id, &RNA_FileAssetSelectParams, params, &params_ptr);
+
+  uiItemR(row, &params_ptr, "asset_library_ref", 0, "", ICON_NONE);
+  if (params->asset_library_ref.type != ASSET_LIBRARY_LOCAL) {
+    uiItemO(row, "", ICON_FILE_REFRESH, "FILE_OT_refresh");
+  }
+
+  uiItemS(col);
+
+  file_create_asset_catalog_tree_view_in_layout(asset_library, col, sfile, params);
 }
 
 void file_tools_region_panels_register(ARegionType *art)