When calculating the header section size based on its contents when a
stylesheet is used, the size hints from the stylesheet are used. In case
if the stylesheet specifies only one of the sizes, the other is set to
-1. Because of this the actual content size is ignored.
The solution is to calculate the size based on the application style, in
case if it's not specified in the stylesheet.
Fixes: QTBUG-75615
Change-Id: I3453fa623d75b6b32832edf753de6e3e4e7f5a22
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>
ffac899576