Mosaic is an app which moves and resizes windows of other applications on your Mac. In order to achieve this we have to use a system called Accessibility which gives Mosaic permission to move and resize windows of applications other than itself. For your security you must explicitly grant permission for Mosaic to do this.
The configuration wizard guides you through this process, but here are some more detailed instructions for clarity:
- Click the menu icon at the top left of the screen
- From the system menu choose "System Preferences..."
- Click the "Security & Privacy" icon
- Select the "Privacy" tab at the top of the "Security & Privacy" panel
- In the list on the left choose "Accessibility"
- In the list on the right you should see Mosaic listed. The list is likely disabled
- To allow you to edit the list, if the padlock is closed in the bottom left corner, click the padlock and enter your system admin password when prompted. The list should then be enabled
- Check the box next to Mosaic
- Mosaic should now have access to the accessibility features it requires to function
If the app was displaying a warning icon on the Mosaic status menu icon, it should now revert to the app icon.