I apologize if this is the wrong place to report bugs, I didn't see a bug report button in the WebIDE.
Here is how I duplicated the bug:
1. Right-click one of your files under my pi projects on the left.
2. Choose Rename.
3. Change the name then hit return.
4. Click on the edit document area on the right.
5. Start typing. Your text will continually be inserted before the insertion point causing you to type from right to left instead of left to right.
I think the webIDE is awesome! Thank you for providing it to the community.