Scroll cursor into view when moving cursor

src/textual_paint/paint.css

@@ -42,6 +42,7 @@ Header.-tall HeaderIcon {
 #canvas {
     width: auto;
     height: auto;
+    /* Note: styles.margin is used in cursor position calculations (could be changed to use difference between absolute regions of parent and child or something...) */
     margin: 1 2;
 }
 

src/textual_paint/paint.py

@@ -3199,6 +3199,15 @@ Columns: {len(self.palette) // 2}
                 self.image.selection.copy_from_document(self.image)
                 self.canvas.refresh_scaled_region(select_region)
 
+                # Scroll the canvas area if needed.
+                # TODO: prevent animation for small movements, maybe ideally preserving it for page up/down and home/end.
+                self.editing_area.scroll_to_region(Region(
+                    x * self.magnification + self.canvas.styles.margin.left,
+                    y * self.magnification + self.canvas.styles.margin.top,
+                    self.magnification,
+                    self.magnification,
+                ))
+
             self.canvas.refresh_scaled_region(textbox.region)
 
     def on_paste(self, event: events.Paste) -> None: