Have you ever tried to create tools on a toolbar using an image list, only to find that you must detach the toolbar from the list and reset all the toolbar button properties every time you want to add to the image list? Annoying, isn’t it?
Before adding anything to the image list, cut the toolbar object. Then you can revise the image list with no complaints from the IDE. Provided that you retain all the original image indexes, you can paste the toolbar object back on the form and retain the toolbar’s link to the image list.