mod(mouse): fix input.Mouse.in method

Pass through mouse events where they actually match the corresponding
`Container`. Adopt mouse event accordingly in `Scrollable` `Element`
trait when passing through the mouse event to the scrollable
`Container`.

src/element.zig

@@ -112,6 +112,17 @@ pub fn Scrollable(Event: type) type {
                     // TODO: not just pass through the given size, but rather the size that is necessary for scrollable content
                     try this.container.handle(.{ .resize = size });
                 },
+                .mouse => |mouse| {
+                    std.log.debug("mouse event detected in scrollable element {any}", .{mouse.in(this.size)});
+                    try this.container.handle(.{
+                        .mouse = .{
+                            .col = mouse.col + this.anchor.col,
+                            .row = mouse.row + this.anchor.row,
+                            .button = mouse.button,
+                            .kind = mouse.kind,
+                        },
+                    });
+                },
                 else => try this.container.handle(event),
             }
         }