[0.9.5] "Move to Group" is greyed out if a new group was created from the Sandbox menu

[isaak654]

Describe the bug
On 0.9.5, the context menu entry "Move to Group" is always greyed out if you previously created the group from the Sandbox menu -> Create Box Group. This issue doesn't occur if you create the group from the "Add group" entry.

To Reproduce
Steps to reproduce the behavior:

1. Verify to not have any existing group
2. Create a new group with any name from the Sandbox menu -> Create Box Group
3. If you select any existing box, the context menu entry "Move to Group" is still greyed out

Expected behavior

1. Move to Group should be visible even for the groups created from the Sandbox menu -> Create Box Group
2. Use the "Create Box Group" text string in all occurrences instead of using a different "Add Group" entry here:
   
3. Optionally renaming "Create Box Group" to "Create New Box Group" or "Create New Group" to obtain a better uniformity with "Create New Box".

Additional context
The "Move to Group" bug was also reported on a Wilders post:
https://www.wilderssecurity.com/threads/sandboxie-plus-0-9-3.439524/page-2#post-3030522