Changing extern variable within the EA does not change input mask when reopened

 

I would like to change an input variable value within the EA and show its changes value in the EA input mask.
If a define a variable like a 

extern int myvar = 0;

then I can change its value

myvar += 1;

but when I reopen the input mask I got the same 0 value.
Is that correct? I would like to show the changed value.

 
You can't change predefined values of user inputs.
 
Stefano Piovesan:

I would like to change an input variable value within the EA and show its changes value in the EA input mask.

Build your own input panel using standard controls and CAppDialog.

https://www.mql5.com/en/docs/standardlibrary/controls

Reason: