When using HiDPI with dpi set to 120, the line height of the text becomes too small to acommodate the text heigh. When this happens, some parts of the text are cropped. If there is some ""_"" (underlines) in the text, it is shown as blanks. On dpi 96 this does not happen.
Yeah, line height is sometimes 'bad' :( *** This bug has been marked as a duplicate of bug 379727 ***