What is the background of this feature request? Please describe.
I've improved and updated a lot an extension this product relies on, just wanted it documented here.

Describe what to do for the development of this feature
Currently, you are using GameMaker's default File Picker on macOS, which is not as feature-complete as the one used on Windows via my DialogModule extension. My DialogModule extension on macOS no longer uses a custom-drawn ImGui dialog, instead uses the native AppKit/Cocoa one. Unlike GameMaker's built-in one, it has a File Filter dropdown/popup box for selecting different file types to enable for selection. This can be seen in the screenshot below:

Describe alternatives you've considered
N/A

Additional context
This ticket is just for documentation of purposes. I will submit a pull request which addresses the issue and will mark my pull request in the description saying it fixes this issue.

What is the estimated development time?
I will take care of implementing this myself, no estimated time needed.

Describe the individual development tasks that make up this feature (along with a dev hour estimate)
Ditto.