procedure TForm1.TreeView1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
var
AHittest:Thittests;
begin
AHittest:= TreeView1.GetHitTestInfoAt(x,y) ;
if htNoWhere in AHittest then Caption := '空白';
if htOnButton in AHittest then Caption := '+';
if htOnItem in AHittest then Caption := 'Item';
end;
Value Means the point is
htAbove Above the client area.
htBelow Below the client area.
htNowhere Inside the control, but not on an item.
htOnItem On an item, its text, or its bitmap.
htOnButton On a button.
htOnIcon On an icon.
htOnIndent On the indented area of an item.
htOnLabel On a label.
htOnRight On the right side of an item.
htOnStateIcon On a state icon or bitmap associated with an item.
htToLeft To the left of the client area.
htToRight To the right of the client area.