I can't select "custom". KDevelop continues to keep enabled my previous selection (eg A4). So I can't change the size (mm) that corespond to the dimentions of the paper on which I will print my code.
Can confirm the issue. The print preview dialog though is from the Qt5 libraries, and this bug can be seen with other instances, e.g. in Qt Assistant (Qt 5.7.1 here). Please check and report this with Qt at https://bugreports.qt.io (could not find a related bug report on a quick check).
(In reply to Friedrich W. H. Kossebau from comment #1) > Please check and report this with Qt at https://bugreports.qt.io (could not > find a related bug report on a quick check). Thank you. https://bugreports.qt.io/browse/QTBUG-60041