I am having the same problem in FL 20!!
my screen is 1920 x 1080 with Windows items set to “middle”
the best fit is obtained setting Scaler 2 to 1200 x 840 and font to large
then, if needed, I shrink the GUI a bit with the handle, that in my case is bottom right (not top right) and the visibility is perfectly fine to me
clearly, a way to only increase the width of Scaler, without increasing its height, so to fill entirely the available space, could be even better…
if it doesn’t jeopardize boxes, menus and the so