The current problem I'm facing is that the filters are not compliant as MS-FileDialog does, let me make it clear, when the DEV set the filter, for example, "JGRAM|*.jgram", if I try to select another file, with another extension, the dialog does not filter the files, when typing and pressing ENTER, see:

Please refer to the attached two gif file illustrating the default behavior of the MS OpenFileDialog and the RadOpenFileDialog. 

1. Add a RadPopupEditor on the form and put two RadButtons in its container.

2. Add a RadOpenFileDialog and a MS OpenFileDialog.

3. Use the following code snippet:

        public RadForm1()
        {
            InitializeComponent();
        }

        private void radButton1_Click(object sender, EventArgs e)
        { 
            this.radOpenFileDialog1.InitialDirectory = @"C:\"; 
            this.radOpenFileDialog1.FileName = string.Empty;
            if (this.radOpenFileDialog1.ShowDialog() == DialogResult.OK)
            {
                
                string fileName = this.radOpenFileDialog1.FileName;
                if (this.radOpenFileDialog1.SafeFileNames.ToList().Count() > 0)
                {
                    fileName = this.radOpenFileDialog1.SafeFileNames.First();
                }
                this.Text = fileName;
                 
            }
        }

        private void radButton2_Click(object sender, EventArgs e)
        {
            this.openFileDialog1.InitialDirectory = @"C:\";
            this.openFileDialog1.FileName = string.Empty;
            if (this.openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                
                string fileName = this.radOpenFileDialog1.FileName;
                if (this.openFileDialog1.SafeFileNames.ToList().Count() > 0)
                {
                    fileName = this.openFileDialog1.SafeFileNames.First();
                }
                this.Text = fileName;
                 
            }
        }

Expected: MS OpenFileDialog is top most:

Actual: RadOpenFileDialog is beneath the popup container:

Workaround: 

this.radOpenFileDialog1.OpenFileDialogForm.TopMost = true;

The problem is reproducible with the Demo application >> File Dialogs >> First Look example:

When opening the Folder Dialog (all in default, no changes needed) and then we click between "My PC" and "C:" back and forth quite rapidly, eventually the dialog freezes and after a while throws an unhandled exception. It is important to click between both quite fast for the issue to show.

Two different types of errors may occur:

Use the Demo application >> File Dialogs >> First Look example.  I have tested typing "\\DYORDANOLAP" and hitting Enter and it seems to navigate to the folder only after pressing Enter a second time:

Expected: In the Windows File Explorer, the user is navigated to the respective folder after the first time the user hits Enter.

Currently, the dialogs provide a way to restore the last open directory. The opened directory path will be stored in a private string field of the RadOpenFolderDialog instance. However, in other this to work, the dialogs require the following steps:

• The same dialog instance should be used every time you open the dialog.
• In order for the directory to be saved the directory should be opened. Clicking cancel or the X button won't save the directory.
• Closing the application and then opening it again, or generally when you create a new dialog instance, the last saved directory will get lost.

We could expose a mechanism to cache the last open directory outside of the dialogs, thus allowing you to restore the directory even when the application is closed.