At the moment I have problems with LockRect / UnlockRect, described here: http://archives.free.net.ph/message/20060213.220622.51814d8e.en.html (The sf.net archives broke the attachmet). This is needed for DDraw, and it's also a showstopper for many D3D7 games.
Hmm, what application are you using to test this? (if you haven't already fixed the issue).
I have written a small test app, which I attached to this mail. It works like this: Pressing ESC quits, pressing any other key makes a d3dclear with a color based on the key pressed. This works nice everywhere. On a click with the left mouse button anywhere, the back buffer is locked, filled with 0xff, unlocked and presented. This should fill the screen with a white color, but instead nothing happens.
The app works as it should on nvidia cards, but it fails with mesa software rendering and with the open source radeon driver and fglrx in most cases.
Maybe I can take a look at that this weekend, but no promises.
Stefan