patch.pause_when_minimised.diff

diff -urp openttd-1.7.0.old/src/video/sdl_v.cpp openttd-1.7.0/src/video/sdl_v.cpp
--- openttd-1.7.0.old/src/video/sdl_v.cpp	2017-05-12 19:57:29.568021877 +0300
+++ openttd-1.7.0/src/video/sdl_v.cpp	2017-05-12 19:53:51.471029678 +0300
@@ -13,6 +13,7 @@
 
 #include "../stdafx.h"
 #include "../openttd.h"
+#include "../command_func.h"
 #include "../gfx_func.h"
 #include "../sdl.h"
 #include "../rev.h"
@@ -584,6 +585,14 @@ int VideoDriver_SDL::PollEvent()
 			break;
 
 		case SDL_ACTIVEEVENT:
+			if (!_networking && _game_mode == GM_NORMAL &&
+					(_pause_mode & PM_PAUSED_NORMAL) == PM_UNPAUSED &&
+					(ev.active.state & SDL_APPACTIVE) && !ev.active.gain) {
+				DEBUG(driver, 1, "SDL: minimised window, pausing");
+				DoCommandP(0, PM_PAUSED_NORMAL, 1, CMD_PAUSE);
+				break;
+			}
+
 			if (!(ev.active.state & SDL_APPMOUSEFOCUS)) break;
 
 			if (ev.active.gain) { // mouse entered the window, enable cursor