Certain app stuck on taskbar


Currently using version 2.5.4501.1476, been using the application it since the 0.9 days. OS is Vista Business 32bit.
This has been an issue for quite some time, I just never bothered to report it. The issue still exists in the latest version...
A certain program (and only this one) I have, PL/SQL Developer by Allround Automations, does the hide/show of the window just fine when switching desktops. However, the taskbar button for this app is "stuck" on the taskbar no matter which desktop I switch to.
I can even click it (button sinks in), and it appears to focus it (lose focus of another app window that is actually on current desktop) even though the plsldev app window itself stays hidden.