I decided to make myself a slider. something like this one
I've got some progress but there are some problems.
1) the thingy (Rectangle) won't stay on the bar if I move it too fast.
2) Script uses lots of resources.
Here's my code (Files are attached)
$hGUI = GUICreate("Test", 300, 200, 100, 100)
$Pic1 = GUICtrlCreatePic("", 48, 80, 204, 16)