How can I set the default file filter to "All Files" in OpenDialog?

I'm using the OpenDialog command to allow users to select files. However, the default file filter is set to show only *.dm files (and possibly other file types), which prevents users from easily selecting *.tif files.

Is there a way to automatically change the default file filter to "All Files" so that *.tif files are visible when the dialog opens? I have searched the documentation but haven't found a clear solution.

Any help or pointers to relevant documentation would be greatly appreciated!

This is not so straight forward and an undocumented/unsupported feature of GMS scripting. Try the following (provided a TIFF I/O Handler is available)

{
    object file_filters = NewFileFilterList()
    
    // List of available IO Handlers
    object IOHandlers = ImageIO_GetImageIOHandlers( )
    forEach(object IOHandlerIter ; IOHandlers){
        Result("\n\n NAME      : "+IOHandlerIter.ImageIOHandler_GetHandlerName())
        Result("\n ID        : "+IOHandlerIter.ImageIOHandler_GetHandlerIdentifier())
        Result("\n FormatID  : "+IOHandlerIter.ImageIOHandler_GetFormatId())        
    }
    
    // Adding the TIF Handler's files to the filter
    object tiffHandler = ImageIO_GetImageIOHandlerByName("TIFF Format")
    if (tiffHandler.ScriptObjectIsValid()) 
        tiffHandler.ImageIOHandler_AddFileFilterToFileFilterList(file_filters)
    else
        Throw("TIFF IO-Handler not found")
    
    string ResultPath
    number Resultfilter
    number filter = 73      // Format ID of the handler
    string path = GetApplicationDirectory("open_save",0)
    
    if (!PoseGetFilePathForsaveDialog(ResultPath,ResultFilter, NULL , "Prompt", path,filter,file_filters ))
        Throw("Dialog cancelled.")
        
    Result("\n\n Chosen path: " + resultPath)
    Result("\n Chosen filter: " + resultfilter)
}