Quoted Originally posted by boyadg > "I think mainWin->show() would be more appropriate" That was my logic too, but if I do that, a small, empty window appears. If I combine both mainWin->show() and MyUIClass->show() two windows appear, one with the UI and one empty! So I finally chose to only show MyUIClass. This is actually a mistake in your code. You must make the MyUIClass object a child of mainWin, otherwise you get two independent toplevel windows: Source code 1 2 MyUIClass* centralWidget...
