Fix redraw handling

ponydos.asm

@@ -75,31 +75,34 @@ initialize_screen:
 	mov ch, 0x20
 	int 0x10
 
-draw:
 	; Set up segments for drawing routines
 	push word 0xb800
 	pop es
 
-	call draw_wallpaper
-	
 	mov di, mouse_column
-	call flip_mouse_cursor
-
-	; Draw windows
-	push cs ; Return segment
-	push word mainloop ; Return offset
-	mov bx, [di - mouse_column + window_chain_head]
-	mov ax, 0xf000
-	and ax, bx
-	push ax ; Call segment
-	;push word 0 ; Call offset
-	push cs ; Call offset
-	mov ax, WM_PAINT
-	retf
 
 mainloop:
-	cmp byte [di - mouse_column + redraw], 0
-	jne draw
+	xor al, al
+	xchg byte [di - mouse_column + redraw], al
+	test al, al
+	jz .draw_end
+	.draw:
+		call draw_wallpaper
+
+		call flip_mouse_cursor
+
+		; Draw windows
+		push cs ; Return segment
+		push word .draw_end ; Return offset
+		mov bx, [di - mouse_column + window_chain_head]
+		mov ax, 0xf000
+		and ax, bx
+		push ax ; Call segment
+		;push word 0 ; Call offset
+		push cs ; Call offset
+		mov ax, WM_PAINT
+		retf
+	.draw_end:
 
 	mov bx, [di - mouse_column + mouse_x]
 	shr bx, 1

shell.asm

@@ -65,6 +65,9 @@ initialize:
 	xchg [es:GLOBAL_WINDOW_CHAIN_HEAD], ax
 	mov [next_window2], ax
 
+	; Request repaint
+	mov byte [es:GLOBAL_REDRAW], 1
+
 	; Temporary testing
 	mov ax, cs
 	mov es, ax