Hi Ilian,
I can see it happening with that scenario. I spent a while on this and narrowed it down to the changes in 2013.2 where we added a handler for the WM_GETMINMAXSIZE windows message. The reason we added this was so that our chromed windows wouldn't cover up an auto-hidden Windows taskbar.
I tried a number of things but wasn't able to make any progress on it thus far. I even made a new simple sample project that doesn't use our controls at all and just handles that WM_GETMINMAXSIZE message and shows the same behavior on a standard WPF window. If you would like to contact our support email address and reference this thread, I'll be happy to send it to you and perhaps we can work together to find a way to still handle that Windows message but not have this negative side effect.