Engine: updated Multitasking setting

* Added `[misc] multitasking=[0,1]` to config, acting as a *starting* setting, which may be changed by runtime call to `SetMultitaskingMode`;
* Ensure multitasking mode is overridden by connected external debugger (always on, if possible);
* Let multitasking mode work in "fullscreen desktop" gfx mode (still disabled in exclusive fullscreen);
* Now correctly reset multitasking mode if gfx mode changes.

Engine/ac/game.cpp

@@ -1303,9 +1303,6 @@ void display_switch_out_suspend()
         }
     }
 
-    // restore the callbacks
-    SetMultitasking(0);
-
     switching_away_from_game--;
 }
 

Engine/ac/gamesetup.h

@@ -88,6 +88,7 @@ struct GameSetup
     bool  load_latest_save; // load latest saved game on launch
     ScreenRotation rotation;
     bool  show_fps;
+    bool  multitasking = false; // whether run on background, when game is switched out
 
     DisplayModeSetup Screen;
     String software_render_driver;

Engine/ac/global_game.cpp

@@ -677,21 +677,30 @@ void SetMultitasking (int mode) {
     if ((mode < 0) | (mode > 1))
         quit("!SetMultitasking: invalid mode parameter");
 
-    if (usetup.override_multitasking >= 0)
+    // Account for the override config option (must be checked first!)
+    if ((usetup.override_multitasking >= 0) && (mode != usetup.override_multitasking))
     {
-        Debug::Printf("SetMultitasking: overridden by user config: %d -> %d", mode, usetup.override_multitasking);
+        Debug::Printf("SetMultitasking: overridden by user config: %d -> %d",
+            mode, usetup.override_multitasking);
         mode = usetup.override_multitasking;
     }
 
-    // Don't allow background running if full screen
-    if ((mode == 1) && (!scsystem.windowed))
+    // Must run on background if debugger is connected
+    if ((mode == 0) && (editor_debugging_initialized != 0))
     {
-        Debug::Printf("SetMultitasking: overridden by fullscreen: %d -> %d", mode, 0);
+        Debug::Printf("SetMultitasking: overridden by the external debugger: %d -> 1", mode);
+        mode = 1;
+    }
+
+    // Regardless, don't allow background running if exclusive full screen
+    if ((mode == 1) && gfxDriver->GetDisplayMode().IsRealFullscreen())
+    {
+        Debug::Printf("SetMultitasking: overridden by fullscreen: %d -> 0", mode);
         mode = 0;
     }
 
     // Install engine callbacks for switching in and out the window
-    Debug::Printf("SetMultitasking: mode %d", mode);
+    Debug::Printf(kDbgMsg_Info, "Multitasking mode set: %d", mode);
     if (mode == 0)
     {
         sys_set_background_mode(false);

Engine/main/config.cpp

@@ -372,6 +372,9 @@ void apply_config(const ConfigTree &cfg)
         usetup.mouse_speed_def = StrUtil::ParseEnum<MouseSpeedDef>(
             mouse_str, CstrArr<kNumMouseSpeedDefs>{ "absolute", "current_display" }, usetup.mouse_speed_def);
 
+        // Various system options
+        usetup.multitasking = CfgReadInt(cfg, "misc", "multitasking", 0) != 0;
+
         // User's overrides and hacks
         usetup.override_multitasking = CfgReadInt(cfg, "override", "multitasking", -1);
         String override_os = CfgReadString(cfg, "override", "os");

Engine/main/engine.cpp

@@ -1291,7 +1291,7 @@ int initialize_engine(const ConfigTree &startup_opts)
     // Configure game window after renderer was initialized
     engine_setup_window();
 
-    SetMultitasking(0);
+    SetMultitasking(usetup.multitasking);
 
     sys_window_show_cursor(false); // hide the system cursor
 

Engine/main/engine_setup.cpp

@@ -11,7 +11,6 @@
 // http://www.opensource.org/licenses/artistic-license-2.0.php
 //
 //=============================================================================
-
 #include "core/platform.h"
 #include "ac/common.h"
 #include "ac/display.h"
@@ -20,6 +19,7 @@
 #include "ac/gamesetup.h"
 #include "ac/gamesetupstruct.h"
 #include "ac/gamestate.h"
+#include "ac/global_game.h"
 #include "ac/mouse.h"
 #include "ac/runtime_defines.h"
 #include "ac/walkbehind.h"
@@ -287,6 +287,9 @@ void engine_post_gfxmode_setup(const Size &init_desktop)
     }
     engine_post_gfxmode_mouse_setup(init_desktop);
 
+    // reset multitasking (may be overridden by the current display mode)
+    SetMultitasking(usetup.multitasking);
+
     video_on_gfxmode_changed();
     invalidate_screen();
 }

Engine/main/game_start.cpp

@@ -20,6 +20,7 @@
 #include "ac/common.h"
 #include "ac/characterinfo.h"
 #include "ac/game.h"
+#include "ac/gamesetup.h"
 #include "ac/gamesetupstruct.h"
 #include "ac/gamestate.h"
 #include "ac/global_game.h"
@@ -55,6 +56,7 @@ void start_game_init_editor_debugging()
         return;
 
     // Debugger expects strict multitasking
+    usetup.multitasking = true;
     usetup.override_multitasking = -1;
     SetMultitasking(1);
 

Engine/main/graphics_mode.cpp

@@ -521,8 +521,9 @@ bool graphics_mode_set_dm(const DisplayMode &dm)
         SavedWindowedSetting.Dm = rdm;
     else
         SavedFullscreenSetting.Dm = rdm;
-    Debug::Printf("Succeeded. Using gfx mode %d x %d (%d-bit) %s",
-        rdm.Width, rdm.Height, rdm.ColorDepth, rdm.IsWindowed() ? "windowed" : "fullscreen");
+    Debug::Printf(kDbgMsg_Info, "Graphics mode set: %d x %d (%d-bit) %s",
+        rdm.Width, rdm.Height, rdm.ColorDepth,
+        rdm.IsWindowed() ? "windowed" : (rdm.IsRealFullscreen() ? "fullscreen" : "fullscreen desktop"));
     return true;
 }