Visual Bug in RC11

Having trouble with LMMS? Ask about it here.
I saw in the developer mailing list that there are barely any bugs in the newest RC, but then I installed it and this happens with the Song Editor:
http://imgur.com/a/pDTuB

Are there usually graphics glitches for nearly finished release candidates? Am I missing something?
Did you remember to un-install previous version, before you installed? Looks like a theme issue..?

(... and ....we found new hicups.. so .. but nothing related to your issue
Oh! I'm sorry, I didn't know I had to do that!

I'm sorry, and thank you!
You can install multiple versions at once if you want. When the installer asks what folder you want to install LMMS into, specify a new one! For example, I keep a few versions installed on my machine: the current version is installed to "LMMS", whatever development version I have is installed in "LMMSdev", and I have 4.15 installed into "LMMSold" for legacy reasons. If each version is installed to its own folder, you can point LMMS to look in that particular folder for that version's default theme.
I'am running Linux, and I have more than one version in my computer, on different drive partitions.
and, I share things between the two. Like stuff in my samples, and projects folders..
Both version work, I just need to makes sure that the dependencies are not running before starting the other version.