source/blender/editors/include/UI_interface.h

@@ -239,6 +239,17 @@ enum {
   UI_BUT_OVERRIDDEN = 1u << 31u,
 };
 
+/** #uiBut.dragflag */
+enum {
+  /** By default only the left part of a button triggers dragging. A questionable design to make
+   * the icon but not other parts of the button draggable. Set this flag so the entire button can
+   * be dragged. */
+  UI_BUT_DRAG_FULL_BUT = (1 << 0),
+
+  /* --- Internal flags. --- */
+  UI_BUT_DRAGPOIN_FREE = (1 << 1),
+};
+
 /* Default font size for normal text. */
 #define UI_DEFAULT_TEXT_POINTS 11.0f
 
@@ -881,6 +892,9 @@ bool UI_but_flag_is_set(uiBut *but, int flag);
 void UI_but_drawflag_enable(uiBut *but, int flag);
 void UI_but_drawflag_disable(uiBut *but, int flag);
 
+void UI_but_dragflag_enable(uiBut *but, int flag);
+void UI_but_dragflag_disable(uiBut *but, int flag);
+
 void UI_but_disable(uiBut *but, const char *disabled_hint);
 
 void UI_but_type_set_menu_from_pulldown(uiBut *but);
@@ -1789,9 +1803,12 @@ void UI_but_drag_set_id(uiBut *but, struct ID *id);
 /**
  * Set an image to display while dragging. This works for any drag type (`WM_DRAG_XXX`).
  * Not to be confused with #UI_but_drag_set_image(), which sets up dragging of an image.
+ *
+ * Sets #UI_BUT_DRAG_FULL_BUT so the full button can be dragged.
  */
 void UI_but_drag_attach_image(uiBut *but, struct ImBuf *imb, float scale);
 /**
+ * Sets #UI_BUT_DRAG_FULL_BUT so the full button can be dragged.
  * \param asset: May be passed from a temporary variable, drag data only stores a copy of this.
  */
 void UI_but_drag_set_asset(uiBut *but,
@@ -1808,6 +1825,8 @@ void UI_but_drag_set_name(uiBut *but, const char *name);
  * Value from button itself.
  */
 void UI_but_drag_set_value(uiBut *but);
+
+/** Sets #UI_BUT_DRAG_FULL_BUT so the full button can be dragged. */
 void UI_but_drag_set_image(
     uiBut *but, const char *path, int icon, struct ImBuf *imb, float scale, bool use_free);
 

source/blender/editors/interface/interface.cc

@@ -4224,6 +4224,10 @@ static uiBut *ui_def_but(uiBlock *block,
     but->flag |= UI_BUT_UNDO;
   }
 
+  if (ELEM(but->type, UI_BTYPE_COLOR)) {
+    but->dragflag |= UI_BUT_DRAG_FULL_BUT;
+  }
+
   BLI_addtail(&block->buttons, but);
 
   if (block->curlayout) {
@@ -5890,6 +5894,16 @@ void UI_but_drawflag_disable(uiBut *but, int flag)
   but->drawflag &= ~flag;
 }
 
+void UI_but_dragflag_enable(uiBut *but, int flag)
+{
+  but->dragflag |= flag;
+}
+
+void UI_but_dragflag_disable(uiBut *but, int flag)
+{
+  but->dragflag &= ~flag;
+}
+
 void UI_but_disable(uiBut *but, const char *disabled_hint)
 {
   UI_but_flag_enable(but, UI_BUT_DISABLED);

source/blender/editors/interface/interface_drag.cc

@@ -24,6 +24,7 @@ void UI_but_drag_attach_image(uiBut *but, struct ImBuf *imb, const float scale)
 {
   but->imb = imb;
   but->imb_scale = scale;
+  UI_but_dragflag_enable(but, UI_BUT_DRAG_FULL_BUT);
 }
 
 void UI_but_drag_set_asset(uiBut *but,

source/blender/editors/interface/interface_intern.hh

@@ -86,11 +86,6 @@ enum {
   /* WARNING: rest of #uiBut.flag in UI_interface.h */
 };
 
-/** #uiBut.dragflag */
-enum {
-  UI_BUT_DRAGPOIN_FREE = (1 << 0),
-};
-
 /** #uiBut.pie_dir */
 enum RadialDirection {
   UI_RADIAL_NONE = -1,

source/blender/editors/interface/interface_query.cc

@@ -247,7 +247,7 @@ bool ui_but_contains_point_px_icon(const uiBut *but, ARegion *region, const wmEv
 
   BLI_rcti_rctf_copy(&rect, &but->rect);
 
-  if (but->imb || but->type == UI_BTYPE_COLOR) {
+  if (but->dragflag & UI_BUT_DRAG_FULL_BUT) {
     /* use button size itself */
   }
   else if (but->drawflag & UI_BUT_ICON_LEFT) {