Suppose you’re using the QT Creator to build a window, and the widgets in the window aren’t expanding to fill the window.
You can check the layout doco but it doesn’t help much. The widgets still don’t fill the window, and certainly don’t resize when the window resizes.
The solution, apparently, is to open up your .ui file and right-click on an empty bit of your window. Choose “Lay Out” -> “Lay Out Horizontally”.
(Or you could do Lay Out Vertically, or even a Grid or Form if you know what you’re doing.)
Looks like this links the window with a QHBoxLayout (or QVBoxLayout or whatever). Without this step, my layout was there but not linked to the window.
Thanks to umerlaton for this tip.