See attached example. If you quit via the menu or ⌘-q while the color dialog is open, no problem. But if you run the example in the terminal, open the color dialog and then hit control-C to kill it, the next time you run it, the color panel will be opened automatically by the OS X window restoration feature. (The "memory" which triggers this is in ~/Library/Saved\ Application\ State/com.yourcompany.QTBUG-29161.savedState/windows.plist .) It doesn't seem to happen with QFileDialog or QPrintDialog for some reason.