WP and TinyMCE in the popup window

Hi, I just start creating my very first editor plugin, and I have one question.

I register my own button for editor, and add filter for “mce_external_plugin”. After that in my_plugin.js file I create tinymce windowManager and I load my own custom_window.php file inside that popup window.

My question is, how can I pass selected text to my custom_window.php file?

I know that I can get it inside my_plugin.js file with this code:

tinyMCE.activeEditor.selection.getContent();


…and I can add this:

ed.windowManager.open({
title : 'My Plugin',
file : url + '/custom_window.php',
width : 500,
height : 400,
inline : 1
}, {
plugin_url : url,
my_args : 'my custom args'
});


How can I get this value “my custom args” inside custom_window.php ?

Also, can I add my own tinymce editor in custom_window.php and how?

And at the end, how can I send back to my_plugin.js modified content (to insert in main post editor)?

Cheers