Running textshot.py will open an overlay over the screen, where a rectangle can be drawn over the portion of the screen containing the text the user wishes to copy.
An optional command line argument can specify the language. For example, python textshot.py eng+fra will use English as the primary language and French as the secondary language. The default is eng (English). Make sure that the appropriate data files for Tesseract are installed for other languages.
It is recommended to attach a global hotkey to this tool.
On Windows, one can accomplish this by using an AutoHotkey script; textshot.ahk contains a sample AHK script that can be used. On Ubuntu, open the Keyboard Settings, which shows you all the Gnome shortcuts. At the bottom there is a + button to add your own shortcuts. Click it and set the command to /usr/bin/python3 <path-to-textshot.py>. In case you are using a venv, the python3 path above should point to the venv's python3 instead of the global python3.