Hello i did a debug tool.
Its a small lite-c files, that shows a box on your window. with 3 features:
move : click panel, and hold mouse, to move the panel arround...
Reference: Click a panel, to set value of that panel x and y positions, and then add, the difference to the cursor positions, that way you know where is your mouse , within panel position ( useful to know the position of panel elements etc.. )
Measure: With this tool, you click and while holding, there is a second point ( cursor position) that calculates the pitagoras triangle, so you can know the width of something , or the height, or the lenght of it. the triangle is drawn on the screen..

The mouse position is also shown all the time, under the cursor position...
For this 3 tools, i bet you can handle better UI designing, since its real time, and in game, so you can memorize the values, and then write them on the script. This saves alot of time , at least for me...