In Seditio if you call plug.php?r=yourplug that would call a file from plugins/code/yourplug.php as a standalone without header/footer. I think we need to improve this to be used for AJAX-mode plugins.
AJAX-mode parts of plugins are standalone, without header/footer, without some code in common.php. They should use hook "ajax" and be called this way: plug.php?r=yourplug which will call plugins/yourplug/yourplug.php.
I also propose having multiple "executable" parts of the plugin. For example, if your plugin "my_plugin" contains a standalone part "my_plugin.php" you call it like plug.php?e=my_plugin. At the same time it contains a popup part "my_plugin.popup.php" which can be called like plug.php?o=my_plugin. And finally an AJAX part "my_plugin.ajax.php". So, the name of the part also tells how it can be executed. Alternatively, there could be a parameter to choose a part of plugin when calling: plug.php?r=my_plugin&p=ajax.
What do you think?
May the Source be with you!