QFontComboBox changes wrongly underlying popup with fonts

QFontComboBox changes wrongly underlying popup with fonts on changing font filter.

Launch attached example, don't touch font combo box and check checkbox "Show only monospaced fonts". Click font combo box to see available monospaced fonts. Uncheck checkbox and have a look at available fonts again. Filtering works, but in the list there is no enough space to scroll all fonts, UI will be stricted to count of monospaced fonts.

Secondly: laucnh app, click font combo box, you will see a full list of fonts. Check checkbox to filter, look at the available monospaced fonts. You will see some amount of monospace fonts, and a lot of space with empty items, you can scroll down.

I want to say that space in popup should be adjusted accordingly with set filter.