Fix #30076: RenderLayer area blocks mouse scrolling

In fact all list templates used to block mouse scroll. It's because mouse
scrolls list's scroll bar. But mouse scroll also used to be "eaten" even
if there's no scroll in list template.
This commit makes scroll even be ignored by list templates if there's
no scroll bar on list.

1 files changed, 9 insertions, 7 deletions

diff --git a/source/blender/editors/interface/interface_handlers.c b/source/blender/editors/interface/interface_handlers.c
index cadc57c9881..7e413cf75f7 100644
--- a/source/blender/editors/interface/interface_handlers.c
+++ b/source/blender/editors/interface/interface_handlers.c
@@ -5859,15 +5859,17 @@ static int ui_handle_list_event(bContext *C, wmEvent *event, ARegion *ar)
 			retval= WM_UI_HANDLER_BREAK;
 		}
 		else if(ELEM(event->type, WHEELUPMOUSE, WHEELDOWNMOUSE)) {
-			/* list template will clamp */
-			if(event->type == WHEELUPMOUSE)
-				pa->list_scroll--;
-			else
-				pa->list_scroll++;
+			if(pa->list_last_len > pa->list_size) {
+				/* list template will clamp */
+				if(event->type == WHEELUPMOUSE)
+					pa->list_scroll--;
+				else
+					pa->list_scroll++;
 
-			ED_region_tag_redraw(ar);
+				ED_region_tag_redraw(ar);
 
-			retval= WM_UI_HANDLER_BREAK;
+				retval= WM_UI_HANDLER_BREAK;
+			}
 		}
 	}