delphi 在 DragDrop 的时候，滚动 TreeView
在 DragDrop 的时候，滚动 TreeView
当高度不够的时候
procedure TForm1.TreeView1DragOver(Sender, Source:
TObject; X, Y: Integer;
State: TDragState; var Accept: Boolean);
begin
if (y < 15) then
{On
the upper edge - should scroll up
}
SendMessage(TreeView1.Handle,
WM_VSCROLL, SB_LINEUP, 0)
else if
(TreeView1.Height - y <
15) then
{ On
the lower edge - should scroll down
}
SendMessage(TreeView1.Handle,
WM_VSCROLL, SB_LINEDOWN, 0);
Accept
:= Source =
Sender;
if not Accept then
exit;
end;