Strange box on opening

I'm running linux and use a window manager rather than a desktop. When I open Heidi there is a small box in the center of the screen with whatever is behind the Heidi window bleeding through, so if I have a browser open to a page behind the Heidi window whatever is in the browser bleeds through into this box. it can only be resized, it can't be moved or closed so I just push it off to an unused window since it's in the way. Any idea what this is and how to prevent it or at least close it? I thought maybe it was a splash screen, but my boss uses Heidi (but on windows) and I don't see anything there when he opens it.

Perhaps this is due to the following line of code in heidisql.dpr, the main project file:

Application.MainFormOnTaskBar := True

Setting it to False has another - even worse - effect, which I can't recall right now, but I recall that this MainFormOnTaskBar is problematic in either ways. I don't have a solution, just some input.

I can live with it since it's just a keystroke to get it off onto an unused window and out of my way, but if I couldn't do that I really couldn't easily use Heidi. It may just have to do with the window manager instead of desktop somehow, just thought someone may know what it was and how to get rid of it completely. Great job you did here, I came from using only workbench or the cli for many years and have been very impressed with what you folk have created. I flipped you a donation too, keep up the good work.