The color selector on borders has no function.
Otherwise you can specify for each cell it's border width and where it has borders (4 directions)
Since you can't see how a cell is formatted in the editor, you can only overwrite, you have to look into the .pop files to find current formatting.
In there you find a value that details the borders.
I spent a while figuring out what they mean.
The Border takes a value between 0 and 63
Value : Border meaning
1 only left, size 1 2 only top, size 1 3 only bottom, size 1 4 only right, size 1 5 left & right, size 1 6 top & right, size 1 7 top & right & left, size 1 8 ? ... 15 all sides, size 1 [15 different border configs + 1 blank] 16 ? (nothing size 2?) 17 only left, size 2 [=1+16] 18 only top, size 2 19 only bottom, size 2 20 only right, size 2 ... 33 only left, size 3 [=1+16+16] 34 only top, size 3 35 only bottom, size 3 36 only right, size 3 .. 63 all sides, size 4 [= 4*16 - 1]
Which knucklehead had the smart idea to save things like this
Whoever programmed this maybe can explain a bit better what's going on.