prevent opening the settings dialog multiple times * main-window.h: settings dialog is now a guarded pointer and class member * main-window.cc (constructor): initialize settings dialog pointer to 0; (destructor): delete pointer if necessary; (process_settings_dialog_request): only switch to desired tab if settings dialog already exists; * settings-dialog.h: new function show_tab, write_changed_setting provate now * settings-dialog.cc (constructor) do not set desired tab here; (show_tab): but here so it can be called independently (button_clicked): close the dialog when ok or cancel was clicked * settings-dialog.ui: removed accepted/rejected signals from the button box since closing the dialog is now done in settings_dialog::button_clicked

8728cf80b7d84b0ac401debac5b37217aac0d2e2 gnulib-hg