"left of right" should be "left or right".
There's a small (subjective?) English nit in there as well: I believe
that buttons are placed (for example) "on the right" rather than "at the
right".
*
* Determines which buttons should be put in the
* titlebar of client-side decorated windows, and whether they
- * should be placed at the left of right.
+ * should be placed on the left or right.
*
* The format of the string is button names, separated by commas.
* A colon separates the buttons that should appear on the left