Toolbar selection inconvenience

[Ofnuts]

Sorry to disappoint you, but the rule (and it's not Gimp, it's all over the place, since early Windows....) is that what really count is the button release. Try this in most apps (even here on Gimp-forum: in your browser, try the Reply button below), click a button, and while keeping the mouse button pressed move the pointer out of the button, then release. You'll see that the button press is ignored. And it's not just buttons, it also applies to checkboxes, radio buttons, etc... (there are exceptions, such as with repeat-on-hold widgets like spinners...)

Otherwise, Gimp lets you use bigger buttons, and if you are in a hurry, there are keyboard shortcuts