Report was that move-to-layer menu failed. The real cause was more complex; had to dive deep in the dungeons of the interface code that handled undos and operators. Found several issues: - popup menus (like redo operator, color picker) executed again on a mouse-exit - far too many buttons were sending undo pushes; even worse, in the operator redo-panel each button action was pushed twice - in case operator redo-buttons have own callbacks (like layer buttons) the redo wasn't working - layerbutton menu was called without creating a proper undo/redo case Things should all work smoother now! On todo: - better definition and handling of all versions for operator menus (four types now, not fun) also: make operator "do" menu, which on first action does operator and then switches to redo-ing - bring back Undo menu, to list the undo stack and jump in it.