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.

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.

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.)

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.

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 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?