In the Desktop App, running on Windows.
The upper right X button to close the window is not in the far corner. This makes it difficult to click.
Consider making it like all other Windows, where the X button is at the furthest upper right. This is so that if the window is maximized, the user can quickly close the window without needing to aim carefully.
This is called Fitt’s Law.
“If you put a target in the corners of the screen, what you have essentially done there is create a target that is infinitely wide.”