This is my example code:
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<StackLayout VerticalOptions="Start" HorizontalOptions="Start" Padding="30">
<Label Text="Entry typing Vietnamese (Telex unicode)"/>
<Entry/>
<BoxView HeightRequest="1" BackgroundColor="Gray"/>
<combobox:SfComboBox HeightRequest="40" x:Name="comboBox" IsEditableMode="True">
<combobox:SfComboBox.ComboBoxSource>
<ListCollection:List x:TypeArguments="x:String">
<x:String>1920 x 1080</x:String>
<x:String>1680 x 1050</x:String>
</ListCollection:List>
</combobox:SfComboBox.ComboBoxSource>
</combobox:SfComboBox>
</StackLayout>
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At Entry, I typing "AA" text will be become "Â" => Ok
At SfCombobox, I typing "AA" text will be becom "Aa" => Not ok (because Im using Telex keyboard)
Attachment:
ComboBoxSampleUnicode_21a1ffbb.zip