Your question has already been answered in the support ticket that you have opened on the same topic. Please, see our answer there for more information. However, I am posting the solution suggested by my colleague, Dess, here as well in order the community to benefit from it.
In order to apply the Fluent theme to RadOpenFileDialog, it is necessary either to drag the Fluent theme from the toolbox and drop it onto the form or create the theme at run time as follows:
FluentTheme fluentTheme = new FluentTheme();
Telerik.WinControls.UI.RadOpenFileDialog opfDialog = new Telerik.WinControls.UI.RadOpenFileDialog();
opfDialog.OpenFileDialogForm.StartPosition = FormStartPosition.CenterScreen;
opfDialog.OpenFileDialogForm.ThemeName = "Fluent";
Additional information about using the default themes is available in the following help article: https://docs.telerik.com/devtools/winforms/styling-and-appearance/using-default-themes
We kindly ask you to use just one thread for a specific problem to contact us. Posting the same questions numerous times slows down our response time because we will need to review and address two or more tickets instead of one. Moreover, threads are handled according to license and time of posting, so if it is an urgent problem, we suggest you use a support ticket, which would be handled before a forum thread.
Thank you for your understanding.
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