Bosses, the number of the item in my listbox, a vertical scroll bar, scroll the scroll bar to slip, the right to choose an item immediately after the jump in front of a selected item, for example of the listbox I have 50 item, I'm right 49th item, would immediately jump to the selected item, 26 cannot select the 49th item, the left mouse button will not appear this problem, only right click will appear, as a student of my bosses, genuflect is begged to offer me a solution is good!