Exit button [X] does not cover entire top-right window corner

I am using Windows 10 and the [X] (exit) button does not cover the entire top-right area of the window, even when the window is maximized. This is a usability issue for me because:

Normally, to exit an application I move my mouse all the way to the top-right corner of that window and then click. In HeidiSQL, instead of exiting the HeidiSQL application, I end up closing the application BEHIND it. For example, if my VS Code window is maximized, and then I toggle to HeidiSQL (also maximized) and then try to exit HeidiSQL, VS Code is closed instead!

This is a known issue with the material theme. See issue #1217. You may select the default "Windows" theme in Heidisql to overcome it.