Open files in workspace is too greedy. It opens every file containing the substring I entered! (I'm working on a project where the file names have a lot of common substrings.)
I note that some people want it to open several files at once -- I agree, but could we have some way of indicating (like, Ctrl+Enter, say -- please, not something that requires dialog navigation or the mouse!) when we want this behaviour?
The problem occurs when you select several items in the dialog then type in our filter box. The selection does not clear. In fact, the selection remains if you close and reopen the dialog.
For now, select once on the top entry in the dialog. Now you are free to use the filter box. Only one file will open when you press OK.