Task manager menu, titlebar and tabs have disappeared

I was reading a question tonight about our dear friend, the Windows Task Manager and remembered, just then, one particular area of confuzzlement about it that it took me a long time to clear up the first time and it was only by dumb luck I found the solution.

Have you ever discovered your Task Manager in this condition?

Restarting it doesn't help, there are no obvious ways of getting the menu, tabs and taskbar to come back again. So how is this solved exactly?

If you double-click the clear border between the task area and the resizing borders, the task manager expands back to it's regular settings.

This is, without a doubt, one of the weirdest features I have ever come across in Windows.

Hope this helps someone from having to finally solve this by randomly clicking everywhere on the window.