Chris,

Just to be clear...if the user has made changes, you don't want to allow them to open another form, or switch to another form?

Let's say the user has not made any changes. Are you going to allow them to open another form then?

>I have a top level form with a treeview control and the navigation for the various forms of the app that appear to the right of the treeview (the treeview is visible all the time...) The user can launch forms from the nodes of the treeview - in the lostfocus of the forms I want to test for data changes and force the user to either save or undo only if they made changes...
>
>At the moment if I make changes and click the treeview the lost focus fires fine and that's OK but if I again click the treeview the next form loads up (closing and losing the edits of the first form...)
>
>That's my problem...