I've replaced all GtkSpinButton by Inkscape::UI::Widget::SpinButton and, when possible, related GtkAdjustment in Gtk::Adjustment.
There is still some GTK C code related to those widgets when I could not C++ified (especially for signals).
I've tried and compare the patch between my patched Inkscape and 0.48.2 and have seen no difference. Values are well stored, loaded and reseted when needed.
Here is my patch.
I've replaced all GtkSpinButton by Inkscape: :UI::Widget: :SpinButton and, when possible, related GtkAdjustment in Gtk::Adjustment.
There is still some GTK C code related to those widgets when I could not C++ified (especially for signals).
I've tried and compare the patch between my patched Inkscape and 0.48.2 and have seen no difference. Values are well stored, loaded and reseted when needed.