Visual Studio 2010 WPF Project ran in debug or release will not allow drag and drop to any control

Question

I had started a question here: WPF drag and drop files onto TreeView from windows explorer but I just discovered this is a totally different problem that what I thought it was.

I have an extremely simple test case.

I was using a treeview but if I use a simple listbox with no code just the following xaml

<StackPanel Orientation="Vertical">
    <ListBox Height="312" Background="#FFBDD6FF" AllowDrop="True"/>
</StackPanel>

If I run the project in expression blend and drag a file over the listbox I see the arrow and the little square below it that incdicates you can drag and drop.

If I run the same project in visual studio and drag a file over the listbox I get a black circle with a line through it.

What could be wrong with my computer or code that is causing that?

Backhander

I just tested your code exactly on my computer and I get the square in Visual Studio. I would apply all services packs and patches and reboot. – Thirsty

Answer 1

Is it possible that you are running Visual Studio as Administrator and Expression Blend normally?

Vivacious

Yes. Does running as administrator interfere with drag and drop? – Backhander

Yes it does, try starting a notepad.exe instance and drag&drop a file from explorer. See that it will open. Now try the same with an instance started as administrator, which will not open the file – Vivacious

That explains all my problems for the last day and a half then. I also found this bug submission on Microsoft Connect: connect.microsoft.com/VisualStudio/feedback/details/537964/…. I guess if notepad has the same behaivior it isn't really a bug. Some kind of security thing I suppose? – Backhander

No this is not a bug, elevated (in your case VisualStudio) and non-elevated (in your case Explorer) processes are shielded from direct communication with each other. Welcome to the wonderfull world uf UAC – Vivacious

It is called UIPI, take the first google hit. You can't hijack the privileges of an elevated program with D+D. Makes sense, no workaround. And not a real problem to your user. – Vermicide