I really think it has to do with my Xcode testing set up. I have other Vulkan applications and they don't show two windows instead of one. I think this has to do with the Xcode testing setup. Is this the correct Developer Forum to ask this question to? Am I in an exclusive Metal forum?

I really think that this is a problem with my Xcode testing setup. I have other Vulkan applications using Xcode without testing which don't have this problem. Is this the correct Developer Forum to ask? Is this an exclusive Metal forum?

I think that it is the Xcode testing setup. Can you take a look at that? I have other Xcode, Vulkan applications that don't have this problem. Is this exclusively a Metal forum? Is this not the correct Developer Forum to ask my question? Sorry- I didn't mean to make so many comments. I thought my comments didn't post and got a pop-up stating I should try posting again in a few minutes. So sorry.

Hello, Great idea! I wrote my question up on Vulkan's reddit page 3 days ago, https://www.reddit.com/r/vulkan/comments/1m06jgy/why_does_this_workaround_fix_the_problem_vulkan/ . I was referred to the apple dev forums, https://developer.apple.com/forums/thread/765445 . As of Apr 2025 there is no determination as to the root of the problem. But I am opening two apps, not just opening two windows. The post says its a problem with the CAMetalDisplayLink. (I'm not really sure what that means.)

If you do look into the problem, the reddit post, https://www.reddit.com/r/vulkan/comments/1m06jgy/why_does_this_workaround_fix_the_problem_vulkan/ , uses github code called BlackSpider. The BlackSpider code is paired down, only opens a window. (The Orange Spider code (referenced above) has extra unused code.) The Black Spider code uses GLFW to open a window; its not calling a Vulkan method. Link to Black Spider is https://github.com/flocela/BlackSpider . Please open BlackSpider/main.cpp.

As I'm re-reading this (2 month2 later). I have now changed (in Utilities.cpp) #include "Utilities.cpp" to #include "Utilities.hpp". So a change from ".cpp" to ".hpp". Don't know how the ".cpp" was working earlier, but it was. And ".hpp" works also.