I'm looking for tutorial or documentation how can one develop plug-in for Sencha Touch, maybe a plug-in that extend the Panel, but with extra layer or functionality, or totally new features.
Can someone point me to the documentation page as I'm a bit lost searching for it.
I'm not sure there is a good piece of documentation for the process around creating a plugin, though for the most part it's quite specific to the plugin itself. I'd recommend checking out the source code for the ListPaging and PullRefresh list plugins (see the src/plugin folder in the SDK download). They're well documented and really not particularly scary.
The only thing you really need to understand is that the plugin's init function will be called when the Component is created - everything else is done from that init function.
I'm not sure there is a good piece of documentation for the process around creating a plugin, though for the most part it's quite specific to the plugin itself. I'd recommend checking out the source code for the ListPaging and PullRefresh list plugins (see the src/plugin folder in the SDK download). They're well documented and really not particularly scary.
The only thing you really need to understand is that the plugin's init function will be called when the Component is created - everything else is done from that init function.