title: Vulkan and transparent windows
body: <p>I'm currently adapting my personal engine to Vulkan and I want to reimplement transparent windows, which I already had with OpenGL.</p>
  <p>I thought that all I need to do is to select the correct color format ( with alpha channel ) and to set the <code>compositeAlpha</code> property of <code>VkSwapchainCreateInfoKHR</code>to <code>VK_COMPOSITE_ALPHA_POST_MULTIPLIED_BIT_KHR</code>.</p>
  <p>However clearing the window with a full transparent color doesn't provide the expected results. It's fully opaque.</p>
  <p>Of course my window system, which didn't change since I had OpenGL, supports it and when I just disable the rendering I also can't click through at the supposed position of the window, this tells me that it's there.</p>
  <p>Are there any other required changes to make this work?</p>
  <h3>Some infos</h3>
  <p>The image format is <code>VK_FORMAT_B8G8R8A8_UNORM</code> and I oriented the vulkan setup as found in <a href="https://github.com/SaschaWillems/Vulkan/" rel="nofollow noreferrer">Sascha Willems examples</a>.</p>