Did this used to work in VS2010 in the last version of VA you were using? If so, do you have any idea which version that was?
This is working correctly for me, and I don't recall anyone else reporting this, so its not a global problem, which is something. Now we just need to find out why this is happening to you.
Do you use any programs that might alter how your mouse works? E.g. software to support extra mouse buttons? Software to change how the mouse pointers look?
Do you have any other extensions installed in VS2010?
Can you try a quick test for me please, type in something like:
strTe| // at this point you should have a short listbox, a suggestion listbox
strTestingListboxes.| // at this point you should have a member listbox
Assuming you get the two different sized listboxes, does the mouse work correctly with either listbox? I suspect both listboxes will behave the same, but its good to find out, and not assume.
For me, single clicking into either listbox selects the item I click on, and leaves the listbox visible. If I double click into the listbox then the listbox is closed and the item I double clicked on is inserted.
If you use Alt-m to show the list of methods in the file and click into this list with the mouse what happens? For me a single click closes this list and jumps to the function I clicked on.