when you drag something to a folder in you bookmarks side pane with the right mouse button and then choose cancel, then the icon in the side pane is not updated to the closed folder icon again but stays with the open folder icon.
Fixed with revision 23745. 2006-11-05 Benedikt Meurer <benny@xfce.org> * thunar/thunar-shortcuts-view.c(thunar_shortcuts_view_drag_leave): Schedule a repaint of the shortcuts pane after resetting the folder drop icon. Bug #2498.