KVIRC 4.2.0 issues rendering bold fonts (kerning?)

0.4.10-RC-29-gf6a9392 gcc dbg lin, VBox 4.3.12, VBEMP
KVIRC 4.2.0 from rapps

Select the german localization when installing the app to get comparable screenshots

The main app has issues rendering fonts in bold.

observed result
0.4.10-RC-29-gf6a9392_vs_KVIRC4_2_0.png
0.4.10-RC-29-gf6a9392_vs_KVIRC4_2_0.log
Please note especially, that the word "klicken" is not bold at all, many other bold text is very poorly kerned.

expected result
2k3sp2.png