What is the proportion in the GUI

I used GTK to do the GUI tutorial. Now I want to know what is the relationship between the coordinates of the XYZ axis in his interface and the mm and inch in reality. I hope someone can answer this question. thank you

I'm not sure anyone understands exactly what you are asking. Can you give more explanation or an example of what you are asking?

After I use my GUI interface, I run the G code. For example, after g0x1, the x-axis information display on my interface goes 25.4. I need to change something to make me use g0x1, and the x-axis information also displays 1. 

If G0x1 sends X to 25.4 then that indicates that the G-code is in Imperial mode and the DRO display is in Metric mode.

Look at the G20 / G21 commands and also the display options of the GUI.

OK, thank you very much for your reply. My question has been solved through your answer. Thank you very much