centralize the invert decision logic to avoid updates to 7 ports

This will make it easier to tinker for best results.

src/mapglyph.c

@@ -438,4 +438,26 @@ const char *str;
     putstr(window, attr, decode_mixed(buf, str));
 }
 
+/*
+ * Window port helper function for menu invert routines to move the decision
+ * logic into one place instead of 7 different window-port routines.
+ */
+boolean
+menuitem_invert_test(mode, itemflags, is_selected)
+int mode;
+unsigned itemflags;     /* The itemflags for the item               */
+boolean is_selected;    /* The current selection status of the item */
+{
+    boolean skipinvert = (itemflags & MENU_ITEMFLAGS_SKIPINVERT) != 0;
+    
+    if ((iflags.menuinvertmode == 1 || iflags.menuinvertmode == 2)
+        && !mode && skipinvert && !is_selected)
+        return FALSE;
+    else if (iflags.menuinvertmode == 2
+        && !mode && skipinvert && is_selected)
+        return TRUE;
+    else
+        return TRUE;
+}
+
 /*mapglyph.c*/

src/options.c

@@ -311,6 +311,7 @@ static struct Comp_Opt {
     { "horsename", "the name of your (first) horse (e.g., horsename:Silver)",
       PL_PSIZ, DISP_IN_GAME },
     { "map_mode", "map display mode under Windows", 20, DISP_IN_GAME }, /*WC*/
+    { "menuinvertmode", "behaviour of menu iverts", 5, SET_IN_GAME },
     { "menustyle", "user interface for object selection", MENUTYPELEN,
       SET_IN_GAME },
     { "menu_deselect_all", "deselect all items in a menu", 4, SET_IN_FILE },
@@ -2362,6 +2363,24 @@ boolean tinitial, tfrom_file;
         return retval;
     }
 
+    /* menuinvertmode=0 or 1 or 2 (2 is experimental) */
+    fullname = "menuinvertmode";
+    if (match_optname(opts, fullname, 5, TRUE)) {
+        if (negated) {
+            bad_negation(fullname, FALSE);
+            return FALSE;
+        } else {
+            int mode = atoi(op);
+
+            if (mode < 0 || mode > 2) {
+                config_error_add("Illegal %s parameter '%s'", fullname, op);
+                return FALSE;
+            }
+            iflags.menuinvertmode = mode;
+	}
+	return retval;
+    }
+
     fullname = "msghistory";
     if (match_optname(opts, fullname, 3, TRUE)) {
         if (duplicate)
@@ -5614,7 +5633,9 @@ char *buf;
                                   : (i == MAP_MODE_ASCII_FIT_TO_SCREEN)
                                     ? "fit_to_screen"
                                     : defopt);
-    } else if (!strcmp(optname, "menustyle"))
+    } else if (!strcmp(optname, "menuinvertmode"))
+        Sprintf(buf, "%d", iflags.menuinvertmode);
+    else if (!strcmp(optname, "menustyle"))
         Sprintf(buf, "%s", menutype[(int) flags.menu_style]);
     else if (!strcmp(optname, "menu_deselect_all"))
         Sprintf(buf, "%s", to_be_done);