Some advice:
GCLS accepts a color argument to clear the screen with, so, instead of doing GCLS:GPAINT 0,0,RGB(255,255,255), you could just do
GCLS RGB(255,255,255)instead of drawing individual squares at each frame, what you could do is gather touch points along multiple frames and draw lines between those gathered touch points. A simple example may be:
DIM TM DIM TX0,TY0'the point that is "now" DIM TX1,TY1'the point that is "then" WHILE 1 TX1=TX0:TY1=TY0'set tx1 & ty1 to be the previous values of tx0,ty0 TOUCH OUT TM,TX0,TY0 IF TM>1 THEN'greater than 1 so that both points 0 and 1 are set GLINE TX0,TY0,TX1,TY1,#WHITE ENDIF WENDHere's a key to some code I wrote for drawing lines like GLINE but with thickness: L5VQ8334 if you're interested