I don't know about Open/Save dialogs, but you can get a list of open explorer windows with COM automation, the Shell.Application object has a collection of windows, or CoCreate IID_IShellWindows directly, each window in the list has a refresh method.

I don't know about C#, but here are examples for WSH and c++

I don't know about Open/Save dialogs, but you can get a list of open explorer windows with COM automation, the Shell.Application object has a collection of windows, or CoCreate IID_IShellWindows directly, each window in the list has a refresh method.

WSH/JScript:

for(var sw=new ActiveXObject("Shell.Application").Windows(),i=0;i<sw.Count; ++i)
   sw.Item(i).Refresh();

I don't know about C#, but here are examples dealing with shell windows in WSH/JScript and c++