ExpanderTemplate malfunction
Hello, I have spent some time trying to fix this but my conclusion is that this requires a fix.
I have a tree and can see which item is currently selected, and I want to change the colour if an item is currently selected/pressed on.
The ItemSelectorTemplate is working as intended, and switch colour correctly. This contain the item-text, and the ExpanderTemplate contains the expander-icon.
I use labels for the ItemSelectorTemplate, and triggers to detect and change colour. ExpanderTemplate does not allow labels to change the default icon, even if, this would not solve the issue. A trigger on a label does not fire correctly when used in the ExpanderTemplate, the trigger works correctly in ItemSelectorTemplate.
If I use FontImageSource, I can change the icon in ExpanderTemplate, but without a built in way to trigger a change. I managed to build my own, but this solution suffer from the same problem that occur when using a label with trigger (cannot change icon) ; the colour of the icon is not correctly changing.
Case:
Expander is now using labels for visual purpose, cannot change icon when using a label in ExpanderTemplate. When a Expander-icon is not selected it is green. The text (ItemSelectorTemplate) and colour is False and white, indicating it is not selected.
I now selecting the top expander-item (whole row).
Expected result:
The text change to True from false, the text colour turns red from white and the expander-icon background turns red from green.
Actual result:
The text and text colour from the ItemSelectorTemplate change correctly, but not the background of the Expander-icon. This should change to red colour since there is a clear indication that the item is selected. The ItemSelectorTemplate and ExpanderTemplate are using the same binding.
Case:
I expand the top expander and move down to the first child (which is a expander).
Expected result:
The text and textcolour on the expander-item on the top level changes back to False and white text colour. The expander icon shall be green since it is no longer selected (should had been red when it was selected). The new selected item's text and colour shall be True and red colour, and the icon shall be red.
Actual result:
The top-expander is now triggered and changes colour. The new selected item changes text and text colour correctly, but not the expander background. When expanding the new item, it turns red.
Summary: The text and text colour in ItemSelectorTemplate consistently change correctly. The ExpanderTemplate is not behaving and changes incorrectly. When the label has been triggered it cannot be reversed and stays red, when its supposed to return to green colour when not selected. This is with a label using style/datatriggers. I get the same result when I use a fontimagesouce and a custom-made trigger. The color stays red and does not convert when the item is not longer selected, and only turns red when using the expander and not selecting it.
Even though the entire item-row it selected, the ExpanderTemplate is only responding when actually using the expander. The ItemTemplateSelector is responding when targeting the row, as intended.
If you attempt to recreate this, set the expander-icon color to white and black instead. This will further demonstrate why this is a problem.
I have an issue with colors when changing UserAppTheme. AppThemeBinding consistently set the Background and TextColor correctly. When using a binding (e.g. IsSelected), the color does not change correctly.
<treeView:SfTreeView.ExpanderTemplate>
<DataTemplate >
<Grid>
<Label
Text="+"
FontSize="Small"
VerticalTextAlignment="Center"
BackgroundColor="{AppThemeBinding Light=Black, Dark=White}"
TextColor="{Binding Content.IsSelected, Converter={StaticResource converter}}"
/>
</Grid>
</DataTemplate>
</treeView:SfTreeView.ExpanderTemplate>
Dark-mode TextColor: Light-mode TextColor:
Selected: Red Selected: Orange
Not selected: Green Not selected: Blue
--change-theme--> 
Background correctly changed color, but not TextColor. Result after each item has been selected;
The TextColor should change in same the way as background.
