I was testing this and noticed that you are still on the beta. If you turn off show pre-release and update does the same problem still occur?
This is probably a user issue... but I've not been able to downgrade.
In Impulse, I right-click the Stardock icon, and select Preferences.
Under General, I deselect Show Pre-Release (Alpha/Beta) versions and click OK to accept the change.
I right-click the Stardock icon and choose Check for application updates.
No 'updates' are found.
Short of uninstalling/re-installing (which I'm hesitant to do) is there a reliable method of downgrading from alpha/beta versions to the most recent release version of WB?
[Updated]
After posting, I downloaded/installed the current beta (as of the time of this posting). That introduced a new set of issues, including a WB prompt indicating that I needed to disable anti-spyware/virus software and/or run an additional process if after rebooting that notice still appeared. It did, and my taskbar was no longer skinned. Fiddled a bit with trying to get it to apply the skin, then just uninstalled WB, re-installed the non-beta release version. This eliminated the 'new' issue introduced with the current beta version, but testing demonstrated that the issue outlined in this topic remains.
So, SeaBass, to answer your short question with a long answer, "Yes, the problem I described with titlebar skins not being applied correctly when a window is sized to take up the entire desktop area does exist in the release version on my system."