1. I have user1 and user2 system users with their respective home directories /home/user1 and /home/user2 in the same server (their will be more ones in future).
2. As usual, PHP configuration and so Drupal's too is to use /tmp directory as temporary directory
3. Both of them installed Drupal 7 and Omega Tools.
4. user1 tried to create a new sub-theme by Omega Tools and he secceded.
5. user2, after user1, also tried to create a new sub-theme by Omega Tools and he did not secceded.
6. So user2 was interested about the reason and looked to the logs of Drupal and saw this MESSAGE: Omega Tools could not create the directory temporary://omega-tools/THEME_NAME-897464c8.
7. user2 looked to the directory /tmp and found there omega-tools/ directory which had already been created by user1 and owned by user1. So user2 could not overwrite it and exception raise Omega Tools could not create the directory
8. I solved this problem by manually changing Drupal's file systems settings for TMP directory and pointed there for user2 the directory /home/user2/tmp
9. But this is not an out-of-the-box solution and may confuse newbuys in future so I propose maintaners to modify tmp file creation function not to use a directory temporary://omega-tools/ but omit omega-tools/ directory creation and use this temporary://THEME_NAME-897464c8 with unique id so there will be no more conflict with file permission and ownership