Firstly if its just a look-and-feel thing, then sorry, too many other things to do.. Same response applies if you don't have an actual problem that needs GTK or a piece of GTK functionality.
I'd also add the I've recently been getting increasingly disillusioned
with GTK desktops. The developers seem to be determined to emulate all
the MS problems that drove us away in the first place. I'm on Linux
precisely because I don't want those "issues".
I think we need to remind people that applications should be desktop
independent. The desktop should not be part of the OS.
My first question is what exactly is the feature you need, then why do you need it and then do you know enough about the internals of GTK to advise whether that feature could be added (or even just emulated) without doing a full conversion to GTK?
On the subject of conversion to GTK, the first thing I would observe
is that it would be non-trivial. FTree is about 30k lines of source and
a lot of them are dealing with the GUI/user interaction.
The simplest way of dealing with it might be a GTK based Xforms
compatability library that emulated xforms in GTK. This would actually
be a useful set of components for others too. Taking this concept
further, what would be more sensible still, would be to go the whole hog
and build a wxWindows xforms library. This would have real benefits for
platform independance.
For anyone in the least bit serious about this, here is a simple list of the functions that I use and that would need to be emulated..
fl_activate_form(), fl_activate_object(), fl_add_box(), fl_add_browser(), fl_add_browser_line(), fl_add_button(), fl_add_canvas(), fl_add_canvas_handler(), fl_add_checkbutton(), fl_add_choice(), fl_add_frame(), fl_add_input(), fl_add_labelframe(), fl_add_menu(), fl_add_slider(), fl_add_tabfolder(), fl_add_text(), fl_add_timeout(), fl_add_valslider(), fl_addto_choice(), fl_addto_tabfolder(), fl_bgn_form(), fl_bgn_group(), fl_call_object_callback(), fl_calloc(), fl_check_forms(), fl_check_input(), fl_clear_browser(), fl_deactivate_form(), fl_deactivate_object(), fl_default_window(), fl_deselect_browser(), fl_do_forms(), fl_end_form(), fl_end_group(), fl_enumerate_fonts(), fl_form_is_visible(), fl_freeze_form(), fl_get_app_resources(), fl_get_border_width(), fl_get_browser(), fl_get_browser_line(), fl_get_browser_maxline(), fl_get_browser_screenlines(), fl_get_browser_topline(), fl_get_button(), fl_get_canvas_id(), fl_get_choice(), fl_get_display(), fl_get_flcolor(), fl_get_focus_object(), fl_get_form(), fl_get_input(), fl_get_menu(), fl_get_menu_item_mode(), fl_get_object_geometry(), fl_get_slider_value(), fl_get_winsize(), fl_hide_form(), fl_hide_object(), fl_initialize(), fl_input_changed(), fl_input_clear_changed(), fl_input_set_changed(), fl_prepare_form_window(), fl_raise_form(), fl_redraw_form(), fl_redraw_object(), fl_register_raw_callback(), fl_remove_timeout(), fl_reset_cursor(), fl_select_browser_line(), fl_set_atclose(), fl_set_border_width(), fl_set_browser_hscrollbar(), fl_set_browser_scrollbarsize(), fl_set_browser_topline(), fl_set_browser_vscrollbar(), fl_set_button(), fl_set_choice(), fl_set_choice_entries(), fl_set_cursor(), fl_set_focus_object(), fl_set_font_name(), fl_set_form_callback(), fl_set_form_minsize(), fl_set_form_position(), fl_set_form_size(), fl_set_goodies_font(), fl_set_input(), fl_set_input_filter(), fl_set_input_hscrollbar(), fl_set_input_return(), fl_set_input_vscrollbar(), fl_set_menu(), fl_set_menu_item_mode(), fl_set_object_boxtype(), fl_set_object_callback(), fl_set_object_color(), fl_set_object_dblbuffer(), fl_set_object_gravity(), fl_set_object_label(), fl_set_object_lalign(), fl_set_object_lcolor(), fl_set_object_lsize(), fl_set_object_lstyle(), fl_set_object_prehandler(), fl_set_object_resize(), fl_set_slider_bounds(), fl_set_slider_filter(), fl_set_slider_size(), fl_set_slider_value(), fl_set_text(), fl_show_alert(), fl_show_file_selector(), fl_show_form(), fl_show_form_window(), fl_show_fselector(), fl_show_message(), fl_show_object(), fl_show_question(), fl_unfreeze_form(), fl_update_display(), fl_winisvalid(), fl_winmove(), fl_winposition(), fl_winreparent(), fl_winresize(),
For what its worth, thats about 128 functions. I got the list using something like
grep fl_ *.c | strstr fl_ | grep '(' | awk 'BEGIN{FS="("}{print $1 "(),"}' | sort | uniq
which is not perfect, but gives a good rough idea! In addition there is all the stuff that accesses xforms data structs...
I admit, the size of that list even surprised me.
The simple summary is, that if someone developed an easy migration path, I would certainly consider it. And since Xforms is now open source, there is nothing now to stop you building just that. So once you have the Xforms to GTK conversion library working, let me know, I'll try a build.