[TreeDataGrid] Row selection needs improving

[clintsinger]

Describe the bug

On the TreeDataGrid when one clicks on a row it will only be selected if the user clicks on the rendered column element. For example, if using a TextColumn only clicking on the text will cause the row to select. One should be able to select any part of the row to select it.

To Reproduce

1. Create a TreeDataGrid with any number of columns.
2. Click on the white space of the row
3. Observe that the row is not selected.
4. Click on the rendered element, such as the text in a column
5. Observe that the row is selected.

Expected behavior

One should be able to click on any part of a row to select it.

Avalonia version

Avalonia: 11.3.0, Avalonia.Controls.TreeDataGrid: 11.1.1

OS

No response

Additional context

No response

[maxkatz6]

Do you use Fluent theme with Fluent theme styles of TreeDataGrid?
By default, TreeDataGridRow should have a transparent (not null) background, which then can be hittested and trigger selection.

[maxkatz6]

Actually, I don't see background actually having a value there: https://github.com/AvaloniaUI/Avalonia.Controls.TreeDataGrid/blob/master/src/Avalonia.Controls.TreeDataGrid/Themes/Generic.axaml#L159-L161

Should be an easy fix/workaround by setting a background on the row.

[clintsinger]

So it turns out I wasn't using the default theme (I had placed it in the wrong part of my app.xaml... I'm still new).

It would still be great if it would work correctly without the theme. Perhaps that's what you are proposing above.