title: Force widget resizing in Qt
body: <p>I'm writing an image viewer, and I'd like some behavior from Qt:</p>
  
  <p>imagine the viewer displays the image in a 256x256 box. Now I want that ctrl+Z do a zoom + resizing of the window; ie. show the 2x zoomed image in a 512x512 box, how can I do that?</p>
  
  <p>Also, imagine know the user gave a certain shape to my viewer, and that he presses F10, I want to change the layout to display the viewer in the same size (if possible, eg not overflowing the screen) and add additional controls under it, and resize the complete widget in a way that the viewer widget does </p>