HelenOS sources

ui_slider_groove_margin  289 uspace/lib/ui/src/slider.c 	rect.p0.x = pos.x + ui_slider_btn_w / 2 - ui_slider_groove_margin;
ui_slider_groove_margin  292 uspace/lib/ui/src/slider.c 	    ui_slider_groove_margin;
HelenOS homepage, sources at GitHub