FilterTemplate now exposes filter state directly through its context. You can use context.FilterIcon to follow the grid’s configured empty/filled filter icons automatically, or context.IsFiltered if you want to switch to your own custom icons.

Example:

<FilterTemplate>
    <MudIconButton OnClick="@OpenFilter" Icon="@context.FilterIcon" Size="@Size.Small" />
    ...
</FilterTemplate>

If you want completely custom icons:

<FilterTemplate>
    <MudIconButton OnClick="@OpenFilter"
                   Icon="@(context.IsFiltered ? MyFilledIcon : MyEmptyIcon)"
                   Size="@Size.Small" />
    ...
</FilterTemplate>

This keeps the feature focused on FilterTemplate instead of adding more DataGrid icon parameters.

Supersedes #12922, #8428, #6238
Relies on #13004
Closes #7478
Closes #10701

Checklist:

• I've read the contribution guidelines
• My code follows the style of this project
• I've added or updated relevant unit tests