 <p>Use a <code>QToolButton</code> instead of a <code>QPushButton</code> and clear its maximum size.</p> <p>You may need to set the vertical size-policy to "Preferred" so that it to has the same height as the other buttons. To get a flat button, check the "autoRaise" property.</p> <p>A quick way to change the button class is to right-click it and select "Morph Into" from the context menu.</p>