[Lazarus] DBNavigator: why is the refresh button enabled only if the dataset is modifiable?

[Juha Manninen]

On Wed, Oct 16, 2019 at 6:11 PM Luca Olivetti via lazarus
<lazarus at lists.lazarus-ide.org> wrote:
> In lcl/include/dbcustomnavigator.inc, method
> TDBCustomNavigator.EditingChanged
>
> CanModify:=Enabled and FDataLink.Active and FDataLink.DataSet.CanModify;
> ...
> Buttons[nbRefresh].Enabled:=CanModify;

I don't know DBNavigator well. It has 2 sets of buttons, the "Buttons"
and then "FocusableButtons". What are those?
The same TDBCustomNavigator.EditingChanged method also has:
  FocusableButtons[nbRefresh].Enabled:=Enabled and FDataLink.Active
and not FDataLink.Editing;
Maybe the same conditions would apply to Buttons[nbRefresh] as well.

Juha