Implement setting custom colours by number

pyte/screens.py

@@ -544,6 +544,19 @@ def set_icon_name(self, param: str) -> None:
         """
         self.icon_name = param
 
+    def set_color_number(self, index: int, color: str) -> None:
+        """Set colour number index to be the specified colour (in hex)
+        """
+        # TODO: This has no way to reset colors back to their original.
+        if index > 15:
+            g.FG_BG_256[index] = color
+        elif index > 7:  # Bright colors
+            g.FG_AIXTERM[index + 82] = color
+            g.BG_AIXTERM[index + 92] = color
+        else:
+            g.FG_ANSI[index + 30] = color
+            g.BG_ANSI[index + 40] = color
+
     def carriage_return(self) -> None:
         """Move the cursor to the beginning of the current line."""
         self.cursor.x = 0

pyte/streams.py

@@ -376,6 +376,9 @@ def create_dispatcher(mapping: Mapping[str, str]) -> Dict[str, Callable[..., Non
                     listener.set_icon_name(param)
                 if code in "02":
                     listener.set_title(param)
+                if code == "4":
+                    index, color = param.split(";")
+                    listener.set_color_number(int(index), color[4:].replace("/", "").lower())
             elif char not in NUL_OR_DEL:
                 draw(char)