diff --git a/build.sh b/build.sh
index 348f669..86f72df 100755
--- a/build.sh
+++ b/build.sh
@@ -20,5 +20,5 @@ cc -std=c89 -DDEBUG -Wall -Wno-unknown-pragmas -Wpedantic -Wshadow -Wextra -Werr
 # cc uxn.c emulator.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -L/usr/local/lib -lSDL2 -o bin/emulator
 
 # run
-./bin/assembler examples/devmouse.usm bin/boot.rom
+./bin/assembler examples/devchord.usm bin/boot.rom
 ./bin/emulator bin/boot.rom
diff --git a/emulator.c b/emulator.c
index 600549d..4a36cd0 100644
--- a/emulator.c
+++ b/emulator.c
@@ -258,22 +258,27 @@ init(void)
 void
 domouse(SDL_Event *event)
 {
+	Uint8 flag = 0x00;
 	int x = clamp((event->motion.x - PAD * 8 * ZOOM) / ZOOM, 0, WIDTH - 1);
 	int y = clamp((event->motion.y - PAD * 8 * ZOOM) / ZOOM, 0, HEIGHT - 1);
-	devmouse->mem[0] = (x >> 8) & 0xff;
 	devmouse->mem[1] = x & 0xff;
 	devmouse->mem[2] = (y >> 8) & 0xff;
 	devmouse->mem[3] = y & 0xff;
-	devmouse->mem[4] = event->button.button == SDL_BUTTON_LEFT;
 	devmouse->mem[5] = 0x00;
+	switch(event->button.button) {
+	case SDL_BUTTON_LEFT: flag = 0x01; break;
+	case SDL_BUTTON_RIGHT: flag = 0x10; break;
+	}
 	switch(event->type) {
 	case SDL_MOUSEBUTTONUP:
-		devmouse->mem[4] = 0;
-		devmouse->mem[5] = 0x10;
+		setflag(&devmouse->mem[4], flag, 0);
 		break;
 	case SDL_MOUSEBUTTONDOWN:
-		devmouse->mem[4] = event->button.button == SDL_BUTTON_LEFT;
-		devmouse->mem[5] = 0x01;
+		setflag(&devmouse->mem[4], flag, 1);
+		if(flag == 0x01 && getflag(&devmouse->mem[4], 0x10))
+			devmouse->mem[5] = 0x01;
+		if(flag == 0x10 && getflag(&devmouse->mem[4], 0x01))
+			devmouse->mem[5] = 0x10;
 		break;
 	}
 }
diff --git a/examples/devchord.usm b/examples/devchord.usm
new file mode 100644
index 0000000..07844cb
--- /dev/null
+++ b/examples/devchord.usm
@@ -0,0 +1,234 @@
+( mouse )
+
+:dev/r fff8 ( std read port )
+:dev/w fff9 ( std write port )
+
+&Point2d { x 2 y 2 }
+
+;pos Point2d
+;mouse Point2d
+;scenter Point2d
+
+( drawing ) ;color 1 ;x1 2 ;x2 2 ;y1 2 ;y2 2 ;i 2
+( window )  ;wx1 2 ;wy1 2 ;wx2 2 ;wy2 2 
+;state 1
+
+|0100 @RESET 
+
+	#01 =color
+
+	#01 =dev/r ( read screen for size )
+
+	#02 =dev/w ( write to screen )
+
+	,paint-pattern JSR
+
+	#01 =dev/w ( write to screen )
+
+	#00 IOR2 #0002 DIV2 =scenter.x
+	#02 IOR2 #0002 DIV2 =scenter.y
+
+	~scenter.x #0060 SUB2 
+	~scenter.y #0018 SUB2 
+	~scenter.x #0060 ADD2 
+	~scenter.y #0018 ADD2 ,paint-window JSR
+
+	#05 =dev/r ( set dev/read mouse )
+	#02 =dev/w ( set dev/write to sprite ) 
+
+	#09 =color
+
+	,window_name ~scenter.x #0058 SUB2 ~scenter.y #0018 SUB2 ,draw-label JSR
+
+BRK
+
+|c000 @FRAME
+
+	( clear last cursor )
+	#10 ,clear_icn ~mouse.x ~mouse.y ,draw-sprite JSR
+	( record mouse positions )
+	#00 IOR2 =mouse.x 
+	#02 IOR2 =mouse.y
+	#11 =state
+
+	( detect click )
+	#04 IOR #11 NEQ ,no-click12 ROT JMP? POP2
+		#10 =state
+		,mouse12_text #0040 ~scenter.y ,draw-label JSR
+		~color ,mouse12_icn #0030 ~scenter.y ,draw-sprite JSR
+		,end-click JSR
+	@no-click12
+	#04 IOR #01 NEQ ,no-click1 ROT JMP? POP2
+		#12 =state
+		,mouse1_text #0040 ~scenter.y ,draw-label JSR
+		~color ,mouse1_icn #0030 ~scenter.y ,draw-sprite JSR
+		,end-click JSR
+	@no-click1
+	#04 IOR #10 NEQ ,no-click2 ROT JMP? POP2
+		#13 =state
+		,mouse2_text #0040 ~scenter.y ,draw-label JSR
+		~color ,mouse2_icn #0030 ~scenter.y ,draw-sprite JSR
+		,end-click JSR
+	@no-click2
+	( default )
+	,mouse0_text #0040 ~scenter.y ,draw-label JSR
+	~color ,mouse0_icn #0030 ~scenter.y ,draw-sprite JSR
+	@end-click
+
+	( detect chord )
+	#05 IOR #01 NEQ ,no-chord1 ROT JMP? POP2
+		,chord1_text #0040 ~scenter.y #0008 ADD2 ,draw-label JSR
+		,end-chord JSR
+	@no-chord1
+	#05 IOR #10 NEQ ,no-chord2 ROT JMP? POP2
+		,chord2_text #0040 ~scenter.y #0008 ADD2 ,draw-label JSR
+		,end-chord JSR
+	@no-chord2
+	( default )
+	,chord0_text #0040 ~scenter.y #0008 ADD2 ,draw-label JSR
+	@end-chord
+
+	( draw mouse )
+	~state ,cursor_icn ~mouse.x ~mouse.y ,draw-sprite JSR
+
+BRK
+
+@paint-pattern ( nil )
+
+	#01 =dev/r ( read screen for size )
+	#02 =dev/w ( write to sprite )
+
+	#0000 
+	@paint-pattern-loop-hor
+	#0000
+	@paint-pattern-loop
+		( draw ) OVR2 IOW2 DUP2 IOW2 ,pattern IOW2 #01 IOW
+		( incr ) #0008 ADD2 DUP2
+		#00 IOR2 LTH2 ,paint-pattern-loop ROT JMP? POP2
+		POP2
+	( incr ) #0008 ADD2 DUP2
+	#02 IOR2 LTH2 ,paint-pattern-loop-hor ROT JMP? POP2
+	POP2
+
+RTS
+
+@paint-window ( name wx1 wy1 wx2 wy2 )
+
+	=wy2 =wx2 =wy1 =wx1
+
+	( Draw background )
+	#00 =color
+	~wx1 #0003 ADD2 ~wy1 #0003 ADD2 ~wx2 #0003 ADD2 ~wy2 #0003 ADD2 ,fill-rect JSR
+	#02 =color
+	~wx1 ~wy1 ~wx2 ~wy2 ,fill-rect JSR
+	( draw outline )
+	#01 =color
+	~wx1 ~wy1 ~wx2 ~wy2 ,line-rect JSR
+	#01 =color
+	~wx1 #0002 ADD2 ~wy1 #0002 ADD2 ~wx2 #0002 SUB2 ~wy2 #0002 SUB2 ,line-rect JSR
+
+RTS
+
+@draw-label ( text x1 y1 )
+	=pos.y =pos.x
+	@draw-label-loop
+		( draw ) ~pos.x ~pos.y IOW2 IOW2 DUP2 LDR #00 SWP #0008 MUL2 ,font ADD2 IOW2 ~color IOW
+		( incr ) #0001 ADD2
+		( incr ) ~pos.x #0008 ADD2 =pos.x
+		DUP2 LDR #00 NEQ ,draw-label-loop ROT JMP? POP2
+	POP2
+RTS
+
+@fill-rect ( x1 y1 x2 y2 )
+	=y2 =x2 ( stash x1 y1 ) =y1 DUP2 WSR2 =x1
+	@fill-rect-ver
+		RSW2 DUP2 =x1 WSR2
+		@fill-rect-hor
+			( draw ) ~x1 ~y1 IOW2 IOW2 ~color IOW
+			( incr ) ~x1 #0001 ADD2 DUP2 =x1  
+			~x2 LTH2 ,fill-rect-hor ROT JMP? POP2
+		~y1 #0001 ADD2 DUP2 =y1
+		~y2 LTH2 ,fill-rect-ver ROT JMP? POP2
+	RSW2 POP2
+RTS
+
+@line-rect ( x1 y1 x2 y2 )
+	=y2 =x2 ( stash x1 y1 ) DUP2 WSR2 =y1 DUP2 WSR2 =x1
+	@line-rect-hor
+		( draw ) ~x1 ~y1 IOW2 IOW2 ~color IOW
+		( draw ) ~x1 ~y2 IOW2 IOW2 ~color IOW
+		( incr ) ~x1 #0001 ADD2 DUP2 =x1  
+		~x2 #0001 ADD2 LTH2 ,line-rect-hor ROT JMP? POP2
+	( restore x1 y1 ) RSW2 =x1 RSW2 =y1
+	@line-rect-ver
+		( incr ) ~y1 #0001 ADD2 DUP2 =y1  
+		( draw ) ~x1 ~y1 IOW2 IOW2 ~color IOW
+		( draw ) ~x2 ~y1 IOW2 IOW2 ~color IOW
+		~y2 #0001 SUB2 LTH2 ,line-rect-ver ROT JMP? POP2
+RTS
+
+@draw-sprite
+	IOW2 ( y byte )
+	IOW2 ( x byte )
+	IOW2 ( sprite address )
+	IOW ( layer-color )
+	RTS
+
+@pattern     [ 0814 2241 8041 2214 ]
+
+@clear_icn   [ 0000 0000 0000 0000 ]
+@cursor_icn  [ 80c0 e0f0 f8e0 1000 ]
+
+@mouse0_icn  [ 7c82 92ee 8282 4438 ]
+@mouse1_icn  [ 7cf2 f2ee 8282 4438 ]
+@mouse2_icn  [ 7c9e 9eee 8282 4438 ]
+@mouse12_icn [ 7cfe feee 8282 4438 ]
+
+@font ( spectrum-zx font ) 
+[
+	0000 0000 0000 0000 0000 2400 7e3c 0000 0000 2400 3c42 0000 0000 6c7c 7c38 1000
+	0010 387c 7c38 1000 0038 387c 6c10 3800 0010 387c 7c10 3800 0000 0018 1800 0000
+	007e 4242 4242 7e00 0000 1824 2418 0000 0018 2442 4224 1800 001e 063a 4a48 3000
+	0038 446c 107c 1000 000c 0808 0838 3800 003e 2222 2266 6600 0000 0822 0022 0800
+	0000 1018 1c18 1000 0000 0818 3818 0800 0008 1c00 001c 0800 0028 2828 2800 2800
+	003e 4a4a 3a0a 0a00 000c 3046 620c 3000 0000 0000 0000 ffff 0010 3800 3810 0038
+	0008 1c2a 0808 0800 0008 0808 2a1c 0800 0000 0804 7e04 0800 0000 1020 7e20 1000
+	0000 4040 7e00 0000 0000 0024 6624 0000 0000 1038 7c00 0000 0000 007c 3810 0000
+	0000 0000 0000 0000 0008 0808 0800 0800 0014 1400 0000 0000 0024 7e24 247e 2400
+	0008 1e28 1c0a 3c08 0042 0408 1020 4200 0030 4832 4c44 3a00 0008 1000 0000 0000
+	0004 0808 0808 0400 0010 0808 0808 1000 0000 1408 3e08 1400 0000 0808 3e08 0800
+	0000 0000 0008 0810 0000 0000 3c00 0000 0000 0000 0000 0800 0000 0204 0810 2000
+	003c 464a 5262 3c00 0018 2808 0808 3e00 003c 4202 3c40 7e00 003c 421c 0242 3c00
+	0008 1828 487e 0800 007e 407c 0242 3c00 003c 407c 4242 3c00 007e 0204 0810 1000
+	003c 423c 4242 3c00 003c 4242 3e02 3c00 0000 0008 0000 0800 0000 0800 0008 0810
+	0000 0810 2010 0800 0000 003e 003e 0000 0000 1008 0408 1000 003c 4202 0c00 0800
+	003c 425a 5442 3c00 0018 2442 7e42 4200 007c 427c 4242 7c00 003c 4240 4042 3c00
+	0078 4442 4244 7800 007e 407c 4040 7e00 003e 4040 7c40 4000 003c 4240 4e42 3c00
+	0042 427e 4242 4200 003e 0808 0808 3e00 0002 0202 4242 3c00 0044 4870 4844 4200
+	0040 4040 4040 7e00 0042 665a 4242 4200 0042 6252 4a46 4200 003c 4242 4242 3c00
+	007c 4242 7c40 4000 003c 4242 524a 3c00 007c 4242 7c44 4200 003c 403c 0242 3c00
+	00fe 1010 1010 1000 0042 4242 4242 3c00 0042 4242 4224 1800 0042 4242 5a66 4200
+	0042 2418 1824 4200 0082 4428 1010 1000 007e 0408 1020 7e00 000c 0808 0808 0c00
+	0040 2010 0804 0200 0018 0808 0808 1800 0008 1422 0000 0000 0000 0000 0000 7e00
+	0008 0400 0000 0000 0000 1c02 1e22 1e00 0020 203c 2222 3c00 0000 1e20 2020 1e00
+	0002 021e 2222 1e00 0000 1c22 3c20 1e00 000c 101c 1010 1000 0000 1c22 221e 021c
+	0020 202c 3222 2200 0008 0018 0808 0400 0008 0008 0808 4830 0020 2428 3028 2400
+	0010 1010 1010 0c00 0000 6854 5454 5400 0000 5864 4444 4400 0000 3844 4444 3800
+	0000 7844 4478 4040 0000 3c44 443c 0406 0000 2c30 2020 2000 0000 3840 3804 7800
+	0010 103c 1010 0c00 0000 4444 4444 3800 0000 4444 2828 1000 0000 4454 5454 2800
+	0000 4428 1028 4400 0000 4444 443c 0438 0000 7c08 1020 7c00 000c 0810 1008 0c00
+	0008 0808 0808 0800 0030 1008 0810 3000 0000 0032 4c00 0000 3c42 99a1 a199 423c
+]
+
+@chord0_text   [ no chord ] <1 .00
+@chord1_text   [ chord 1_ ] <1 .00
+@chord2_text   [ chord _2 ] <1 .00
+@mouse0_text   [ no click ] <1 .00
+@mouse1_text   [ mouse 1_ ] <1 .00
+@mouse2_text   [ mouse _2 ] <1 .00
+@mouse12_text  [ mouse 12 ] <1 .00
+@window_name   [ mouse test ] <1 .00
+
+|d000 @ERROR BRK 
+|FFF0 [ 25fd c3d2 a7bf ] ( palette )
+|FFFA .RESET .FRAME .ERROR
diff --git a/examples/devmouse.usm b/examples/devmouse.usm
index f851703..ed77f3b 100644
--- a/examples/devmouse.usm
+++ b/examples/devmouse.usm
@@ -12,7 +12,7 @@
 
 |0100 @RESET 
 	
-	#01 =dev/r ( set dev/read mouse )
+	#01 =dev/r ( set dev/read screen )
 
 	( position cat )
 	#00 IOR2 #0002 DIV2 =cat.x 
diff --git a/examples/label.usm b/examples/label.usm
index 939c3dc..8da0a38 100644
--- a/examples/label.usm
+++ b/examples/label.usm
@@ -38,6 +38,7 @@ BRK
 		( incr ) #0001 ADD2
 		( incr ) ~x1 #0008 ADD2 =x1
 		DUP2 LDR #00 NEQ ,draw-label-loop ROT JMP? POP2
+	POP2
 RTS
 
 @font ( spectrum-zx font ) 
diff --git a/examples/window.usm b/examples/window.usm
index c08dd42..437c9ba 100644
--- a/examples/window.usm
+++ b/examples/window.usm
@@ -77,7 +77,7 @@ RTS
 
 RTS
 
-@paint-window ( wx1 wy1 wx2 wy2 )
+@paint-window ( name wx1 wy1 wx2 wy2 )
 
 	=wy2 =wx2 =wy1 =wx1 =wname
 
@@ -167,6 +167,7 @@ RTS
 		( incr ) #0001 ADD2
 		( incr ) ~x1 #0008 ADD2 =x1
 		DUP2 LDR #00 NEQ ,draw-label-loop ROT JMP? POP2
+	POP2
 RTS
 
 @texture       [ aa55 aa55 aa55 aa55 ]