1) make the file chooser dialog native. At the moment this is disabled since on the mac there is a difficulty: a native file open dialog do not allow to type the file name. You have to take different actions in the case of a file load or a file save and the old texmacs api didn't differentiate the two possibilities. Now Joris has made some changes and when the dialog has to be created we know if it is for a load or a save, so that in principle we can choose the right native widget. Relevant lines in Graphics/Gui/widget.hpp are
widget file_chooser_widget (command cmd, string type, bool save);
// file chooser widget for files of a given 'type';
// for files of type "image", the widget includes a previsualizer for images
// 'save' indicates whether we intend to save the file