In TelerikSelectBase that the DropDownList inherits, the FieldIdentifier is set only in the OnInitializedAsync method and therefore the FieldIdentitier is never updated. This can cause issues with validation as seen in this example:  https://blazorrepl.telerik.com/GyamPdlf37LXpPAW36.

To reproduce:

• Select the last item in the tree 7.Garden and change the value in the drop down list to Unsupported - the drop down list shows a red border.
• Select item 6.Garden from the tree. (Any item in the tree other than 1 will do) - I expect the drop down to not have the red border, yet is does.

For reference, in the TelerikInputBase, the FieldIdentifier is set in the SetParameterAsync and thus it is accordingly updated. See the TextBox behavior in the above sample.

When the user opens a filterable DropDownList or Combobox on a mobile device, the search box is initially focused, and the system keyboard opens. This way, the keyboard hides part of the listed items.

I have added a Filterable DropDownList inside the TelerikForm. When I select a value from the popup and tab away the focus class still denotes that the component is focused even though it is not. 

Opening the DDL through the expand button and selecting an item results in focus loss

Run the OnChange sample in debug mode. Then, select a value after clicking the input box and try the same after clicking the arrow icon. 

I have a cascading DropDownList scenario with virtual scrolling. When the first DropDownList changes value, the second one should reset its scrollbar to the top, because it now contains new data. This doesn't happen.

Here is a REPL test page.

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ADMIN EDIT

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As a workaround for the time being, you may track when the value is changed in the parent DropDownList to dispose and re-initialize the child DropDownList.

Here is an example: https://blazorrepl.telerik.com/mdafHabk585ZtzyV54.

On a tablet, when the DropDownList, the MultiSelect or the ComboBox components are clicked, any appearance or disappearance of the tablet keyboard will cause them to display an empty popup.

This only happens if the popup somehow could otherwise overflow the viewport, i.e. only when the DropDownList, the MultiSelect or the ComboBox component are very close to the bottom of the viewport.

The validation Tooltip does not show correctly when hovering from the icon to the select element in the DropDownList

When I place a DropDownList inside a Modal Window and run it in Safari there is a flicker in the UI when the dropdown is expanded.