See bug 374011 comment 87. I looked at the gtk2 nsFilePicker.cpp, and it doesn't use the default filename provided in modes other than "save". It should, to actually implement the nsIFilePicker API.

I would have thought this patch would fix it, but the filepicker completely ignores this setting (including not even highlighting this file!).

For open dialogs you need to use gtk_file_chooser_set_filename() instead. I'm not sure what the effect is on relative paths or non-existent files, though.

Michael, could you roll a patch for this?

With the way the GTK dialog behaves, this will have no effect unless the filename given exists in the requested folder. If it does exist, it will be preselected and the the filename filled in the textbox. I also decided to fix some little errors I found in the code. Its much easier to read now that we got rid of all that ridiculous dynamic linking.

Pushed 48e090c98118

This doesn't work over here (FC9, Firefox trunk build with this patch). Just load the attachment page for this bug, select a file to attach, then click the file control's "browse" button again. That file doesn't end up selected in the resulting filepicker...

Hmm, this is because we don't change directories to the last one you were in. If your file is in the directory that is first opened when you reopen the file picker, the file is selected.

> Hmm, this is because we don't change directories to the last one you were in. Er, that would be a bug if it happened, no? The file control certainly tells the filepicker to open the parent directory of the currently selected file. But in any case, that's not what I'm seeing. I end up with the right directory. I just don't see the right file selected.

I'm doing a new approach now. That patch did introduce the bug I was seeing because GTK "helpfully" changes directories when you use that function (but since we don't have a directory in that default name GTK always goes to the pwd).

Should we be setting the filename by concatenating the dir and leafname, then?

Yep, I have a working patch for that now. I just need to wrestle with hg to update to tip :(

This applies on top of patch 1.

Pushed 5300ca58f128

Looks great. Thank you!