Unable undrawing of dialogs used in the title-screen

This sets the restore_ flag to true for the obvious dialogs I've found
that are used on the title-screen.

Also, make GUI1 dialogs mark all buttons dirty on a DRAW_ALL_EVENT to
ensure the buttons get redrawn.

src/gui/dialogs/addon_connect.cpp

@@ -58,6 +58,7 @@ taddon_connect::taddon_connect(std::string& host_name,
 							   display*)
 	: allow_remove_(allow_remove)
 {
+	set_restore(true);
 	register_text("host_name", false, host_name, true);
 }
 

src/gui/dialogs/campaign_difficulty.cpp

@@ -79,6 +79,8 @@ tcampaign_difficulty::tcampaign_difficulty(
 	, campaign_id_(campaign["id"])
 	, selected_difficulty_()
 {
+	set_restore(true);
+
 	// Populate local config with difficulty children
 	difficulties_.append_children(campaign, "difficulty");
 

src/gui/dialogs/campaign_selection.hpp

@@ -30,6 +30,7 @@ public:
 		choice_(-1),
 		deterministic_(false)
 	{
+		set_restore(true);
 	}
 
 	/***** ***** ***** setters / getters for members ***** ****** *****/

src/gui/dialogs/network_transmission.cpp

@@ -73,6 +73,7 @@ tnetwork_transmission::tnetwork_transmission(
 	, subtitle_(subtitle)
 {
 	register_label("title", true, title, false);
+	set_restore(true);
 }
 
 void tnetwork_transmission::set_subtitle(const std::string& subtitle)

src/show_dialog.cpp

@@ -168,6 +168,10 @@ void dialog_frame::handle_event(const SDL_Event& event) {
 
 	if (event.type == DRAW_ALL_EVENT) {
 		set_dirty();
+
+		for(std::vector<button *>::iterator it = buttons_->begin(); it != buttons_->end(); ++it) {
+			(*it)->set_dirty(true);
+		}
 	}
 
 	if (event.type == DRAW_EVENT || event.type == DRAW_ALL_EVENT) {