Remove game.shouldreturntoeditor in favor of using defer callback

game.shouldreturntoeditor was added to fix a frame ordering issue that
was causing a bug where if you started playtesting in a room with a
horizontal/vertical warp background, and exited playtesting in a
different room that also had a horizontal/vertical warp background and
which was different, then the background of the room you exited in would
slowly scroll offscreen, when you re-entered the editor, instead of the
background consisting entirely of the actual background of the room.

Namely, the issue was that the game would render one more frame of
GAMEMODE after graphics.backgrounddrawn got set to false, and re-set it
to true, thus negating the background redraw, so the editor background
would be incorrect.

With defer callbacks, we can now just use a couple lines of code,
instead of having to add an extra kludge variable and putting handling
for it all over the code.

desktop_version/src/Game.cpp

@@ -7,6 +7,7 @@
 #include <string.h>
 #include <tinyxml2.h>
 
+#include "DeferCallbacks.h"
 #include "editor.h"
 #include "Entity.h"
 #include "Enums.h"
@@ -365,10 +366,6 @@ void Game::init(void)
     fadetolab = false;
     fadetolabdelay = 0;
 
-#if !defined(NO_CUSTOM_LEVELS)
-    shouldreturntoeditor = false;
-#endif
-
     over30mode = false;
     glitchrunnermode = false;
 
@@ -1902,7 +1899,7 @@ void Game::updatestate(void)
                 }
                 else
                 {
-                    shouldreturntoeditor = true;
+                    returntoeditor();
                     if(!muted && ed.levmusic>0) music.fadeMusicVolumeIn(3000);
                     if(ed.levmusic>0) music.fadeout();
                 }
@@ -6584,6 +6581,11 @@ void Game::returntolab(void)
 }
 
 #if !defined(NO_CUSTOM_LEVELS)
+static void resetbg(void)
+{
+    graphics.backgrounddrawn = false;
+}
+
 void Game::returntoeditor(void)
 {
     gamestate = EDITORMODE;
@@ -6602,7 +6604,7 @@ void Game::returntoeditor(void)
     ed.notedelay = 0;
     ed.roomnamehide = 0;
 
-    graphics.backgrounddrawn=false;
+    DEFER_CALLBACK(resetbg);
     music.fadeout();
     //If warpdir() is used during playtesting, we need to set it back after!
     for (int j = 0; j < ed.maxheight; j++)

desktop_version/src/Game.h

@@ -434,7 +434,6 @@ public:
 
 #if !defined(NO_CUSTOM_LEVELS)
     void returntoeditor(void);
-    bool shouldreturntoeditor;
 #endif
 
     int gametimer;

desktop_version/src/Input.cpp

@@ -1779,7 +1779,7 @@ void gameinput(void)
             }else if(game.activetele && game.readytotele > 20 && game.press_map){
                 //pass, let code block below handle it
             }else{
-                game.shouldreturntoeditor = true;
+                game.returntoeditor();
                 game.mapheld = true;
             }
         }

desktop_version/src/Logic.cpp

@@ -1576,11 +1576,4 @@ void gamelogic(void)
 
     if (game.teleport_to_new_area)
         script.teleport();
-
-#if !defined(NO_CUSTOM_LEVELS)
-    if (game.shouldreturntoeditor)
-    {
-        game.returntoeditor();
-    }
-#endif
 }

desktop_version/src/editor.cpp

@@ -2419,11 +2419,6 @@ static void editormenurender(int tr, int tg, int tb)
 void editorrender(void)
 {
     extern editorclass ed;
-    if (game.shouldreturntoeditor)
-    {
-        graphics.backgrounddrawn = false;
-    }
-
     //Draw grid
 
     ClearSurface(graphics.backBuffer);
@@ -3647,11 +3642,6 @@ void editorlogic(void)
     //Misc
     help.updateglow();
 
-    if (game.shouldreturntoeditor)
-    {
-        game.shouldreturntoeditor = false;
-    }
-
     graphics.titlebg.bypos -= 2;
     graphics.titlebg.bscroll = -2;