(svn r22818) -Fix [FS#4742] (r22796, rlongago): don't spawn threads for world generation and NewGRF scanning when using the dedicated or null video driver regardless of the used blitter

src/video/dedicated_v.h

@@ -29,6 +29,7 @@ public:
 
 	/* virtual */ bool ToggleFullscreen(bool fullscreen);
 	/* virtual */ const char *GetName() const { return "dedicated"; }
+	/* virtual */ bool HasGUI() const { return false; }
 };
 
 /** Factory for the dedicated server video driver. */

src/video/null_v.h

@@ -32,6 +32,7 @@ public:
 
 	/* virtual */ bool ToggleFullscreen(bool fullscreen);
 	/* virtual */ const char *GetName() const { return "null"; }
+	/* virtual */ bool HasGUI() const { return false; }
 };
 
 /** Factory the null video driver. */

src/video/video_driver.hpp

@@ -46,6 +46,19 @@ public:
 	 * @return True if the change succeeded.
 	 */
 	virtual bool ToggleFullscreen(bool fullscreen) = 0;
+
+	/**
+	 * Whether the driver has a graphical user interface with the end user.
+	 * Or in other words, whether we should spawn a thread for world generation
+	 * and NewGRF scanning so the graphical updates can keep coming. Otherwise
+	 * progress has to be shown on the console, which uses by definition another
+	 * thread/process for display purposes.
+	 * @return True for all drivers except null and dedicated.
+	 */
+	virtual bool HasGUI() const
+	{
+		return true;
+	}
 };
 
 /** Base of the factory for the video drivers. */