这个函数已经用过了,都不行
HEADER_SetDragLimit()手册描述如下
Sets the limit for dragging the dividers on or off. If the limit is on, a divider can only be
dragged within the widget area. If the limit is off, it can be dragged outside the widget.
这个函数应该只是限制拖动区域,但是始终可以拖动,其他也找不到更好的库函数了,哎,纠结呀