[581] Revise assumption that ROM toolsprites are always unmasked

Wimp-3_99o introduced an assumption that any toolsprites in ROM are to be
plotted unmasked, and that holds for Ursula and later where the ROM set don't
need the underlying colour (gadgets are always grey and rely on the tintfunc to
make the focus titlebar cream).
The toolsprites in the RISC OS 3.10 ROM however are almost entirely transparent
as their 2D look just plots pixels on top of the underlying fill colour.

Change the logic to look at all the toolsprites and only use the solid plot
SpriteOp if they are all truly solid (skipping the titlebar, since those are
already special cased by dofunkytitlebar and the tintfunc).

s/Wimp10

@@ -728,15 +728,6 @@ maketoollist EntryS "R1-R11"
         MOVMI   R3,#0
         SUBS    R4,R4,#1
         MOVMI   R4,#0                   ; always returns an extra pixel - unhelpful!
-;
-      [ TrueIcon3
-        ; If these are the ROM toolsprites, assume all tools are unmasked
-        LDR     R0,ROMstart
-        LDR     R14,ROMend
-        CMP     R1,R0
-        CMPHS   R14,R1
-        BHS     %FT66
-      ]
 ;
         TEQ     R5,#1
         LDREQ   R5,[sp]
@@ -847,12 +838,12 @@ maketoollist EntryS "R1-R11"
         BL      freetoolarea
         EXITS
 42
+    [ fastborders
       [ Medusa
         MOV     R1, #8+32               ; Plot masked with wide tables by default
       |
         MOV     R1, #8                  ; Plot masked by default
       ]
-      [ fastborders
         LDRB    R0,tsprite_needsfactors ; do we need to do translation
         TEQ     R0,#0
         LDREQ   R0,=&200+SpriteReason_PutSpriteUserCoords
@@ -860,23 +851,37 @@ maketoollist EntryS "R1-R11"
         ADRNEL  R2,tool_scalingblk
         LDRNE   R3,tpixtable_at
         MOVEQ   R3,#0
-      |
-        LDR     R0,=&200+SpriteReason_PutSpriteScaled
-      [ TrueIcon3
-        LDR     R14, tool_area
-        LDR     R2, ROMstart
-        LDR     R3, ROMend
-        CMP     R14, R2
-        CMPHS   R3, R14
+    |
+;
+; to work out the tool plot op, run through the cached tool list to see if any
+; are masked, skipping over the title bar top/bottom as a special case per
+; dofunkytitlebar which will be plotted masked assessed on a per sprite basis
+; (this is a speed optimisation/flicker reduction so that we don't fill with
+; background colour only to then plot over the top with a solid sprite).
+;
+        LDR     R2,tool_list
+        LDR     R3,=toolcachesize       ; -> list / size
+        MOV     R14,#0
       [ Medusa
-        MOVHS   R1, #0+32               ; pretend ROM toolsprites are unmasked
+        MOV     R1,#0+32                ; Plot solid with wide tables by default
       |
-        MOVHS   R1, #0
-      ]
-      ]
+        MOV     R1,#0                   ; Plot solid by default
+      ]
+43
+        TEQ     R14,#tool_tbarmidt
+        TEQNE   R14,#tool_tbarmidb
+        LDRNE   R0,[R2,R14]
+        TSTNE   R0,#1                   ; mask status
+        ORRNE   R1,R1,#8                ; swap to plot masked
+        SUBNE   R14,R3,#4               ; exit FOR
+        ADD     R14,R14,#4
+        CMP     R14,R3
+        BNE     %BT43
+
+        LDR     R0,=&200+SpriteReason_PutSpriteScaled
         ADRL    R2,tool_scalingblk
         LDR     R3,tpixtable_at
-      ]
+    ]
 ;
         ASSERT  tool_maskop = tool_plotop+4
         ASSERT  tool_scaling = tool_maskop+4