The windows menu is not available in the latest sketch update which has the option to merge all the working/open windows into a single window with tabs. Is there any other way to perform this action?
Hey @Arjun, hope you’re doing well!
We just checked and this seems to be working as expected on our end, in our latest release Sketch 99.1
After clicking on the option, all the windows/Documents from Sketch are merged into a single window, with multiple tabs.
It would be good to check on System Settings > Desktop & Dock > Windows section and see if you have the ability for the system to use Tabs on apps that support it.
Let us know if this helps 
One of my colleagues actually replied to Arjun earlier today:
Simply navigate to the top menubar and select "Window ". From there, choose the "Merge all Windows " option, and you should be good to go.
