LibGUI/WindowServer: Implement per-window cursor hiding

userspace/libraries/LibGUI/include/LibGUI/Packet.h

@@ -234,6 +234,7 @@ namespace LibGUI
 			bool alpha_channel;
 			bool resizable;
 			bool shown;
+			bool cursor_visible;
 		};
 
 		DEFINE_PACKET(

userspace/libraries/LibGUI/include/LibGUI/Window.h

@@ -26,6 +26,7 @@ namespace LibGUI
 			.alpha_channel   = false,
 			.resizable       = false,
 			.shown           = true,
+			.cursor_visible  = true,
 		};
 
 	public:
@@ -48,6 +49,8 @@ namespace LibGUI
 
 		void set_position(int32_t x, int32_t y);
 
+		void set_cursor_visible(bool visible);
+
 		Attributes get_attributes() const { return m_attributes; }
 		void set_attributes(Attributes attributes);