added test case for node.Visible and found another two bugs: 1. Set node.Visible not working 2. Keyboard.KeyPressed always return true once pressed, which should only happen in the frame the key is released.
added test case for node.Visible and found another two bugs:
1. Set node.Visible not working
2. Keyboard.KeyPressed always return true once pressed, which should only happen in the frame the key is released.

zwcloud/ImGui,zwcloud/ImGui,zwcloud/ImGui