How can I copy text from dialog boxes and menus?

I am learning Japanese and installed the OS in Japanese to immerse myself in the language. Sometimes I want to copy messages from windows, menus and dialog boxes so that I can look them up on the dictionary, but I cant. I saw that there there many options for doing this in Windows. Are there any similar options available for Ubuntu?

Make a screenshot and use OCR

1. Install OCR software

   sudo apt-get install tesseract-ocr
   sudo apt-get install tesseract-ocr-jpn
   

2. Install a GUI for tesseract

   sudo apt-get install gimagereader
   

3. Make a screenshot of your desktop or of a part of your desktop

4. Start gimagereader and start the recognizion

   

5. Copy the text into the right pane and translate