TYPO3 Core

• open install tool
• go to "Remove temporary assets"
• click one button with a big number, so that it needs some seconds
• meanwhile open Database Compare
• wait until asset deletion is finished
• DB compare will have the disabled "Scan again" buttom from asset removal
• (to recover from this dead view, just close and open DB compare again)

This is probably valid for any combination of Install Tool tools, but with these two I disvovered it. For these two it's just funny because the buttons are initially inactive anyways, but maybe there are panel combinations where you expect an initially enabled button to do something different than it will actually do in the end!

Discovered on v10, likely valid on v11 as well.