To solve the thin Preview window problem;
I've had this problem for years now, it's deeply frustrating and takes hours more of your
valuable time to achieve anything!
After uninstalling and reinstalling, deleting local content and verifying cache all of
which made no difference, I have just solved the width issue by editing the
SkyrimEditorPrefs ini file found in the "Steamapps/common/skyrim" folder.
To edit preview window size
1) Make a copy of the SkyrimEditorPrefs file and call it SkyrimEditorPrefsCOPY, just in
case you accidentally make a hash of it (it happens), save it in the same folder so it's
easy to find if you need it!
2) Open the original file and look under "General" starting at the top, down about 6-8
inches from top of list.
Here is a section of the list with the bit you want to find separated out in green;
Copy the numbers that you see under the iPreview section above and change yours to the
values in green. Save the file in it's original place overwrite if it asks you to.
The original (shown below in red) gives these figures, make sure yours is not in reverse
order as mine was;
As you can see the iPreviewW ( width) is originally set to 158 which is why the box was
so thin. I don't know why this is but assume someone at Bethesda just screwed up, it's
the only box that can't be resized by dragging!
Mine works fine now after years of struggling! Hope it helps you.