Here is an update to my issues with SliceX. I had no problem contacting CoreMelt tech support. The contact page worked fine. My copy is registered so I can't speak to what happens with the trial version. They have been very responsive and we have exchanged several e-mails. Unfortunately nothing has been resolved. The only thing they have been able to replicate is that sometimes option clicking on a point in the mask and selecting delete does not work. This is easily worked around by selecting the point and hitting the delete key on the keyboard which always works and is easier anyway. I have reinstalled SliceX several times, repaired permissions on my boot drive, trashed FCPX preferences, tried a new user. The only thing I haven't done is reinstall 10.8.3 which I don't think would help since I have had these problems with 10.6.8 and 10.8.2. Also had the problems with FCPX 10.0.6, 10.0.7 and now 10.0.8. Here is my current problem list:
1. Option clicking on a point and selecting curve or linear to next or previous point randomly crashes FCP. Once it crashed the computer with a kernal panic. The logs alway point to the VTwinFx plugin as the culprit. In my case this was installed by SliceX. I have found no work around other than not using the option click menu items. This is a problem because some mask shapes like polygons don't give you handles to adjust the curve in/out to the point. You can only get them by option clicking and selecting from the menu.
2. Randomly when I apply a mask it comes up offset and not centered in the viewer. Usually when this happens if you click on a slider in the inspector it will jump in to place.
3. Randomly when you try to select a point in the mask the whole mask jumps around. Sometimes it does this just moving the cursor in the viewer without trying to select anything. Work around is wait because it will come back eventually.
4. Clicking on the mask line to add a point works, but it adds two points so you have to delete one. I have found that if after adding the point you deselect it and reselect it is ok.
5.I have had no problem keyframing the mask shape, but adding keyframes in the inspector sometimes fails and is erratic.
As I said CoreMelt has been good about working with me, but to no success. If they could just solve the crashing problem I would be content. Also I have to say that their help file is woefully inadequate. You really learn by trial and error.