``` import win.ui; /*DSG{{*/ var winform = win.form(text="aardio form";right=759;bottom=469) winform.add() /*}}*/ var rgb = 0; winform.setInterval( 1000,function(){ rgb = gdi.RGB(math.random(0,255),math.random(0,255),math.random(0,255)) winform.bgcolor = rgb; winform.redrawBackground() //同时触发WM_PAINT } ); winform.wndproc = function(hwnd,message,wParam,lParam){ select( message ) { case 0x205/*_WM_RBUTTONUP*/{ //鼠标右键弹起,下面获取坐标 var x,y = win.getMessagePos(lParam); } case 0xF/*_WM_PAINT*/ { gdi.paint( hwnd, function( hdc,width, height,rcPaint,fErase,paintStruct ){ str = string.format("背景颜色每隔一秒变换,背景值为0X%6X", rgb); ::TextOut(hdc,100,100,str,string.len(str)); ::BitBlt(hdc, 0, 0, width, height, hMemDc, 0, 0, 0xCC0020/*_SRCCOPY*/); } ); } else{ } } //无返回值则继续调用默认回调函数 } winform.show(); win.loopMessage(); return winform; ```