Fix apparent oversight in ButtonWidget m_rect initialization.

Author: tobbi

src/editor/button_widget.cpp

@@ -25,7 +25,7 @@ ButtonWidget::ButtonWidget(SpritePtr sprite, const Vector& pos,
                            std::function<void()> sig_click) :
   m_sprite(std::move(sprite)),
   m_rect(pos, Sizef(static_cast<float>(m_sprite->get_width()),
-                    static_cast<float>(m_sprite->get_width()))),
+                    static_cast<float>(m_sprite->get_height()))),
   m_grab(false),
   m_hover(false),
   m_sig_click(std::move(sig_click))