Last Updated: 13 Mar 2023 15:54 by Adam
Release R2 2021 (LIB 2021.1.329)
Created on: 13 May 2020 06:40
Category: FileDialogs
Type: Bug Report
FileOpenDialog: Selecting multiple files is very slow

I use the RadOpenFileDialog with the MultiSelect property set to True. My test folder contains 105 files with sizes about 1 to 2 kb and all the same extension.  If I select multiple files with <ctrl>+<mouse left> the selection behaves as expected. If I select multiple files with <shift>+<mouse left> I have to wait al long time. Unselecting the file by clicking on an unselected entry is also very slow.  If I try to select all files with <ctrl>+<A> the dialog remains busy and does not respond anymore. 

My code for testing is as simple as this:

        private static void TestFileOpenDialog()
            RadOpenFileDialog dlg = new RadOpenFileDialog();
            dlg.InitialDirectory = @"path to files"; // 105 files with sizes from 1 to 2 kb
            dlg.Filter = "my files (*.mal)|.mal";
            dlg.FilterIndex = 0;
            dlg.MultiSelect = true;
            DialogResult result = dlg.ShowDialog();


1 comment
Dess | Tech Support Engineer, Principal
Posted on: 13 May 2020 11:58

Hello, Peter, 

Following the provided code snippet, I have prepared a sample project and tested with a folder containing 100 files. Indeed, selecting multiple files is extremely slow. The attached gif file illustrates the behavior on my end when I select the first file, scroll to the last file in the folder, keep the Shift key pressed and select the last file. This is expected to select all files and takes several minutes on my end. Unselecting a single file is also very slow. Please have in mind that the video is cut in time in order to avoid very long waiting.

The core problem here is the number of tokens that are being created in the autocomplete box in the Filter name field.

I have logged it in our feedback portal by creating a public thread on your behalf. You can track its progress, subscribe for status changes and add your comments on the following link - feedback item.

I have also updated your Telerik points.

Currently, due to the specificity of the internal implementation of the RadAutoCompleteBox control which is used in the dialog, I am unable to suggest an appropriate solution. Please excuse us for the inconvenience caused. 

We will do our best to find an appropriate solution to improve the performance.

Dess | Tech Support Engineer, Sr.
Progress Telerik

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