Sorry for the late reply, so just for the sake completeness:
If you designed layout for some size and then forced it to be that size (which you actually CAN do by calling Ctrl::NoLayoutZoom), then if default GUI font is bigger then "design" font, some labels and text would overflow their's designated areas...
The solution might be to change the default GUI font, which you can do too, but then your app will not be following host platform settings...