Customize stream.publish dialog

[slup]

How can I customize the publish dialog?
I managed to make a customized feed post by using the Facebook.request(String graphPath, Bundle parameters, String httpMethod) method:
mFacebook.request("/me/feed", parameters, "POST"));

parameters:

parameters.putString("link", "...");
parameters.putString("name", "...");
parameters.putString("caption", "...");
parameters.putString("source", "...");
parameters.putString("attribution", "...");

this works as expected, but now I'd like to let the user add a "message" to those parameters using the stream.publish dialog.
At first I tried to call the dialog with "/me/feed" instead of "stream.publish" and the same parameters I used for the request, which wasn't working as I thought, the dialog just said "Error with [App]".
Thus I suppose I can't use the graph-API in the dialog?
Further trying I called dialog with another parameters Bundle:

attachment.putString("caption", "...");
attachment.putString("name", "...");
attachment.putString("href", "...");
parameters.putBundle("attachment", attachment);

But the publish dialog just ignores them, publishing a message (without any extras) still works though. Also adding a key named "message" to parameters works as expected, filling the message input field with the given value.

[slup]

Solved: Put the parameters in a JSON object and encode it to a URL, see: Facebook Connect for Mobile Web
parameters.putString("attachment", "%7B%22name%22%3A%22app+name%22%2C%22caption%22%3A%22app+caption%22%7D");