How to make 'blue' variable?

Hi all, I'm trying to make my own ImageViewer. Using some program as a template, I saw a lot of 'blue' variables in it (when I point on such variable there is a text "The scope of variable ... spans multiple function").

Now I understood, that I want to use such variables also - in callback functions to update text, data, and so on.

How can I create such variables? Short explanation of what does it mean is appreciated as well. Thanks.

Answer 1

[Image Analyst]

Keywords are in pure blue. Global variables are in cyan. You can just put the line

global myVariable;

in any function that needs to see the global variable. Other than that, just create it and use it like any other variable.

[Mikhail]

But in that template there is only one variable defined as global. However there arre a lot of global variables. When I am trying to do that in my program, my callback function doesn't use it as global

[Image Analyst]

Post a screenshot of your screen so we can see it. In nwindows type alt-PrintScreen, then go to http://snag.gy and paste it in and give us the url or click on the green and brown image icon to paste it in your response here.

Answer 2

[Mikhail]

Look! only 1 global variable is defined, however you can see a lot of cyan variables.

[Mikhail]

Got it, in that template he just wrote callback function inside main function. Therefore variables which he used in both main and callback function automatically became cyan. Thanks