Got the installer working. Fixed a few bugs including a nasty-to-debug issue where the lang_id was being hardcoded during installation, resulting in strings being inserted with the wrong lang_id causing an infinfinite loop with fetch() throwing a "no strings" error and using template (which calls fetch()) to complain
tinyMCEPopup.requireLangPack();
var ExampleDialog = {
init : function() {
var f = document.forms[0];
// Get the selected contents as text and place it in the input
f.someval.value = tinyMCEPopup.editor.selection.getContent({format : 'text'});
f.somearg.value = tinyMCEPopup.getWindowArg('some_custom_arg');
},
insert : function() {
// Insert the contents from the input into the document
tinyMCEPopup.editor.execCommand('mceInsertContent', false, document.forms[0].someval.value);
tinyMCEPopup.close();
}
};
tinyMCEPopup.onInit.add(ExampleDialog.init, ExampleDialog);