The arrow button click does not work as expected in the latest release version. This is a regression in our latest 2026.2.702 release, where the AllowedClickButtons property is not initialized correctly. We are working on a fix! Please subscribe to this item, and you will receive an email notification when we introduce the fix.

In the meantime, you can apply the following workaround:

this.radDropDownList1.DropDownListElement.ArrowButton.AllowedClickButtons = MouseButtons.Left;

Or use v.2026.2.520, where the arrow button functions as usual.

We appreciate your patience and apologize for the inconvenience this issue may have caused. 

This item is migrated to the Telerik Document Processing portal: 
http://feedback.telerik.com/Project/184/Feedback/Details/190124 
Please use the new item for commenting, voting and subscribing instead of this one.

Use attached to reproduce.

Workaround:

- Use RadForm it explicitly handles the controls scaling. 
- Make sure that the following of the user controls are set like this:

this.AutoScaleDimensions = new System.Drawing.SizeF(96F, 96F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Dpi;