摘要： Shift 是一个集合变量。type TShiftState = set of (ssShift, ssAlt, ssCtrl, ssLeft, ssRight,ssMiddle, ssDouble);也就是说TShiftstate类型有ssShift, ssAlt, ssCtrl, ssLeft（鼠标左键）,ssRight（鼠标右键）, ssMiddle（鼠标中键）, ssDouble (鼠标双击)Value MeaningssShiftThe Shift key is held down.ssAltThe Alt key is held down.ssCtrlThe Ctrl key is 阅读全文