M include/mgba/internal/gba/renderers/video-software.h → include/mgba/internal/gba/renderers/video-software.h

@@ -120,6 +120,8 @@ struct WindowN {
 		struct GBAVideoWindowRegion h;
 		struct GBAVideoWindowRegion v;
 		struct WindowControl control;
+		int16_t offsetX;
+		int16_t offsetY;
 	} winN[2];
 
 	struct WindowControl winout;

M src/gba/core.c → src/gba/core.c

@@ -1099,6 +1099,10 @@ gbacore->renderer.objOffsetX = x;
 		gbacore->renderer.objOffsetY = y;
 		gbacore->renderer.oamDirty = 1;
 		break;
+	case GBA_LAYER_WIN0:
+		gbacore->renderer.winN[id - GBA_LAYER_WIN0].offsetX = x;
+		gbacore->renderer.winN[id - GBA_LAYER_WIN0].offsetY = y;
+		break;
 	default:
 		return;
 	}

M src/gba/renderers/video-software.c → src/gba/renderers/video-software.c

@@ -443,13 +443,13 @@ }
 
 static void _breakWindow(struct GBAVideoSoftwareRenderer* softwareRenderer, struct WindowN* win, int y) {
 	if (win->v.end >= win->v.start) {
-		if (y >= win->v.end) {
+		if (y >= win->v.end + win->offsetY) {
 			return;
 		}
-		if (y < win->v.start) {
+		if (y < win->v.start + win->offsetY) {
 			return;
 		}
-	} else if (y >= win->v.end && y < win->v.start) {
+	} else if (y >= win->v.end + win->offsetY && y < win->v.start + win->offsetY) {
 		return;
 	}
 	if (win->h.end > GBA_VIDEO_HORIZONTAL_PIXELS || win->h.end < win->h.start) {