Hi,

I have an checkedlistbox with a lot of items, so there is a vertical
scrollbar in the checkedlistbox.
I want to make the checkedlistbox invisible when the mouseleave event goes
off.
The mouseleave event goes off when I move the mouse to the scrollbar. Can
someone explain this to me? Isn't the scrollbar a part of the checkedlistbox?

Huahe wrote:
It is, but it's part of it's non-client area. All Windows windows
(which includes what we think of as forms, and also controls) have a
client area - that part that the window can draw - and a non-client
area - that part that Windows draws. This is most obvious with a
regular Form - the titlebar (including min max buttons etc), and the
border, are the non-client area. As far as the form is concerned, it
only has access to its own client area - so for instance (0,0) is the
top left corner not of the form as the user sees it, but of the bit
within the Windows-drawn border, below the title bar.

It appears MouseLeave is triggred when the client area is left, not the
control as a whole. There are probably two acceptable solutions:

1) As per <http://tinyurl.com/b95mc> you could create a Timer that
watches for when the mouse pointer actually leaves the entire control

2) As per <http://tinyurl.com/9bbcg> you could subclass the listbox and
watch for the non-client mouse messages

Option 1 is probably easier, but neither are particularly elegant.

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