UI: Support dragging tree-view items

Adds the needed bits to the UI tree-view API to support dragging
tree-view items. This isn't used yet, but will be in the following
commit for asset catalogs.

There will probably be some further tweaks to the design at some point,
for now this should work well enough for our use-cases.

1 files changed, 1 insertions, 0 deletions

diff --git a/source/blender/editors/include/UI_interface.h b/source/blender/editors/include/UI_interface.h
index 12fdda2092c..0f290d4255b 100644
--- a/source/blender/editors/include/UI_interface.h
+++ b/source/blender/editors/include/UI_interface.h
@@ -2777,6 +2777,7 @@ void UI_interface_tag_script_reload(void);
 
 bool UI_tree_view_item_is_active(const uiTreeViewItemHandle *item);
 bool UI_tree_view_item_matches(const uiTreeViewItemHandle *a, const uiTreeViewItemHandle *b);
+bool UI_tree_view_item_drag_start(struct bContext *C, uiTreeViewItemHandle *item_);
 bool UI_tree_view_item_can_drop(const uiTreeViewItemHandle *item_,
                                 const struct wmDrag *drag,
                                 const char **r_disabled_hint);