IF you create a new form with the borderstyle set to none and have it accept a GridView in the constructor you can pass an instance of a gridview control that is created on the main form but not added to it. Then the new form can be animated in with EXAnimatedWindow api. and set the passed gridview to dock and fill the new form, then have an event that when it looses focus the new form closes and removes the gridview from the form's control collection as not to be disposed and then whatever changes and selections were made will be available via the original instance as it was only passed as a reference and not a copy.

I know this can sound complicated and it can be. But its really the only way to achieve a real drop down effect as the Show?hide method is sloppy and doesn't have a reusable drop in usability.

Sorry if i didn't explain this well. As I have done it before with the tree view and such I know it works in practice but here I have presented enough theory for you to be able to figure it out.

Multi columns combo. Take a look at codeproject articles :

1. http://www.codeproject.com/KB/combob...BoxLinked.aspx
2. http://www.codeproject.com/KB/combob...lumncombo.aspx