add: WMSetSliderContinuous(s, False); WMSetSliderAction(s, sliderCallback, s);
context: testSlider(WMScreen *scr){    WMWindow *win;    WMSlider *s;    windowCount++;        win = WMCreateWindow(scr, "testSlider");    WMResizeWidget(win, 300, 300);    WMSetWindowTitle(win, "Sliders");    WMSetWindowCloseAction(win, closeAction, NULL);    s = WMCreateSlider(win);    WMResizeWidget(s, 16, 100);    WMMoveWidget(s, 100, 100);    WMSetSliderKnobThickness(s, 8);    s = WMCreateSlider(win);    WMResizeWidget(s, 100, 16);    WMMoveWidget(s, 100, 10);    WMSetSliderKnobThickness(s, 8);    WMRealizeWidget(win);    WMMapSubwidgets(win);    WMMapWidget(win);}