The following image will allow users to select only pdf files.
But, the problem is it would show "PDF FILES" as file description in the file dialog by default. What should I do to display my own custom name for my .mbxml files? I have taken the reference from the post Show custom text for applied file type filters on file dialog to upload particular category of files.
I want to rename the "custom files" (as shown in image1) to "Manifold dataFile" (as shown in image2) and remove the "ALL Files" text from image1 so that only "Manifold dataFile" is shown in the file selection dialog box and users can't select any other file other than .mbxml by selecting the "All Files" text.