Entry not Filling Parent Stack Layout

I am building an entry form with a caption column and a value column. The caption column contains a label and the value columns contains a HorizontalStackLayout which might have an Entry and a search button right next to it. I have the HorizontalStackLayout set to FILL which it does fine. I have the Entry also set to FILL which it does NOT?

//IF THIS IS  A TEXT FIELD
if (cv.GetType() == typeof(Entry)) { ((Entry) cv).HorizontalOptions = LayoutOptions.Fill;
}

//SET CONTROL'S DYNAMIC VIS SETTING
cv.IsVisible = visible;

//IF THIS FIELD IS READONLY
if (trx.is_field_readonly(c)) {
  cv.IsEnabled = false;
}

//ADD CAPTION TO GRID
grid.Add(caption, 0, c);

//USING STACK LAYOUT IN CASE WE NEED TO ADD A SEARCH BUTTON
HorizontalStackLayout hz = new HorizontalStackLayout();
hz.BackgroundColor = Colors.LightGoldenrodYellow;
hz.HorizontalOptions = LayoutOptions.Fill;
hz.Add(cv);

//ADD CONTROL TO GRID
if (trx.is_field_lookup_field(trx.data_field_list[c])) {
  ImageButton search_button = new ImageButton();
  search_button.WidthRequest = 32;
  search_button.HeightRequest = 32;
  search_button.HorizontalOptions = LayoutOptions.Start;
  search_button.Source = "Resources/Images/search.png";
  search_button.BackgroundColor = Colors.LightGray;
  search_button.Padding = 5;
  hz.Add(search_button);
}

//ADD STACKLAYOUT FOR CONTROL(S)
grid.Add(hz, 1, c);

The appearance is this:

Any thoughts on how to get the Entries to fill the HorizontalStackLayout?

Thanks in advance

Fill doesn't do what you expect, when inside a StackLayout.

The Obsolete FillAndExpand does. See Maui discussion LayoutOptions.EndAndExpand is obsolete. Though that is talking about ..AndExpand on End, its a similar issue on Fill.

Either:

• use FillAndExpand (even though it is obsolete).
  Or:
• Use a Grid instead (no stacklayout). This lets you control expansion by ColumnDefinition * vs. Auto. In your case, you'll define the columns differently, depending on whether the row has BOTH Entry AND Image.

Since you are already in a Grid, [I think] the most performant solution, because it avoids nesting layouts, is to add a third column, then use ColumnSpan=2 when you want Entry to fill the space that would be used by Image:

var grid = new Grid()
{
    ColumnDefinitions =
    {
        new ColumnDefinition { Width = GridLength.Auto },  // or whatever you have now.
        new ColumnDefinition { Width = GridLength.Star },
        new ColumnDefinition { Width = GridLength.Auto }
    }
};

...

bool hasImageButton = trx.is_field_lookup_field(trx.data_field_list[c]);
grid.Children.Add(cv, 1, c);
if (!hasImageButton)
    Grid.SetColumnSpan(cv, 2);
if (hasImageButton)
{
    ...
    grid.Children.Add(search_button, 2, c);
}