LibGUI: Implement attributes for windows

Windows can now change whether they have title bar, rounded corners,
alpha channel and whether they are movable. Also windows can also change
their own position

userspace/programs/WindowServer/Window.cpp

@@ -19,7 +19,8 @@ Window::Window(int fd, Rectangle area, long smo_key, BAN::StringView title, cons
 
 	m_fb_addr = static_cast<uint32_t*>(smo_map(smo_key));
 	ASSERT(m_fb_addr);
-	memset(m_fb_addr, 0, client_width() * client_height() * 4);
+
+	memset(m_fb_addr, 0xFF, client_width() * client_height() * 4);
 }
 
 Window::~Window()