The default edge width of windows is a single pixel; that’s very awkward to grab to drag the edges or corners.
It is possible to use ALT + Middle-Mouse-Button + Drag from within the window in the region of the edge or corner. But it would be better if the edges were just a bit thicker. There’s a way to do that too:
You need to know which theme you’re using. (Find that in the Appearance settings.) The default seems to be Ambiance.
As superuser (sudo su), edit the file
Near the top is an element
<frame_geometry name=”frame_geometry_normal” … />
containing three child elements:
<distance name=”left_width” value=”1″/>
<distance name=”right_width” value=”1″/>
<distance name=”bottom_height” value=”1″/>
Change the 1s (ones) to something else. I found 5 (five) to be a practical value.