Merge branch 'master' into jgrpp

# Conflicts:
#	CMakeLists.txt
#	bin/ai/CMakeLists.txt
#	bin/game/CMakeLists.txt
#	src/ai/ai_info.cpp
#	src/company_base.h
#	src/economy.cpp
#	src/game/game_info.cpp
#	src/gfx_type.h
#	src/linkgraph/linkgraph_gui.cpp
#	src/palette.cpp
#	src/palette_func.h
#	src/saveload/saveload.h
#	src/saveload/vehicle_sl.cpp
#	src/ship_cmd.cpp
#	src/train_cmd.cpp
#	src/vehicle_base.h
#	src/window.cpp
#	src/window_func.h

src/network/network_gui.cpp

@@ -1957,7 +1957,7 @@ public:
 			DrawFrameRect(r, button->colour, FR_NONE);
 			DrawSprite(button->sprite, PAL_NONE, r.left + WidgetDimensions::scaled.framerect.left, r.top + WidgetDimensions::scaled.framerect.top);
 			if (button->disabled) {
-				GfxFillRect(r.Shrink(WidgetDimensions::scaled.bevel), _colour_gradient[button->colour & 0xF][2], FILLRECT_CHECKER);
+				GfxFillRect(r.Shrink(WidgetDimensions::scaled.bevel), GetColourGradient(button->colour, SHADE_DARKER), FILLRECT_CHECKER);
 			}
 
 			int width = button->width + WidgetDimensions::scaled.hsep_normal;