[Glade-devel] Property Binding: Fixing the big blocker

[denisw at online.de (Denis Washington)]

Hi,

After an unfortunate longer period of inactivity, I am happy to tell you 
that I started to work on bringing GObject property binding support to 
Glade again where I left off last summer after GSoC [1]. (By the way, I 
passed final evaluation! Thanks to everyone involved! Thank for 
mentoring me, Juan! :) This message is intended as a quick update what I 
am doing now.

In my last message to this list [2], I mentioned that the current Glade 
codebase doesn't record changes to the sensitivity of properties (such 
as, e.g., making the "label" property of a GtkButton insensitive when 
that button is set to have a custom content widget) in its command 
(undo/redo) system, and that this makes it impossible to cleanly 
auto-remove property bindings that become invalid this way. Tristan 
identified this problem as a blocker to the adoption of the property 
binding branch [3] into master, so this is what I'm starting to tackle now.

For this purpose, I created a new branch named "command-set-sensitive" 
to convert all relevant property sensitivity changes to undoable 
commands. (I am not doing this in the "gbinding" branch directly to 
allow for easier isolated reviewing and testing.) The branch introduces 
the following (as loosely discussed with Tristan):

- A new command function, named glade_command_set_property_sensitive(), 
which sets the sensitivity of a single property undoably. Being more of 
a side effect, this command is always group with other commands (such as 
switching the content type of a GtkButton) and should never stand on its 
own.

- A new virtual function of GladeWidgetAdaptor, 
glade_widget_adaptor_adjust_property_flags(), which can be overridden 
for each type of widget to provide a property sensitivity policy. It 
accepts a "use_command" boolean parameter which tells the function 
whether to use the command system for sensititivity changes or call 
glade_widget_property_set_sensitive() directly. (The latter is required 
when the widget is first created, or when it is loaded from a file.)

- A port of a small portion of the GTK+ plugin to the new functions as 
an example. (Currently, only the GtkEntry-related port is ported.)

I hope that this work enables me to fix the last remaining big blocker 
bug before the property binding branch is ready for prime time. Any 
feedback is very welcome! (@Tristan: Please review when you find the time!)

Regards,
Denis

[1] https://live.gnome.org/DenisWashington_GtkBuilder
[2] http://lists.ximian.com/pipermail/glade-devel/2011-September/001902.html
[3] http://git.gnome.org/browse/glade/log/?h=gbinding