Replace triggers on PageExtension with EventSubscriber in CodeUnit

Hello,

I have a page extension for the “ItemList” page (31), among other things to vary the color of the description according to the state of the stock. Here is the part of the code concerned:

    layout
    {
        modify(Description)
        {
            StyleExpr = StyleExprTxt;
        }
    }

    trigger OnAfterGetRecord()
    begin
        StyleExprTxt := OurGlobalFunctions.ChangeItemColorAccordingToStock(Rec."No.");
    end;

    var
        OurGlobalFunctions: Codeunit "OurGlobalFunctions";
        [InDataSet]
        StyleExprTxt: Text[50];

I would like to replace the trigger OnAfterGetRecord with an EventSubscriber in a CodeUnit:

    [EventSubscriber(ObjectType::Page, Page::"Item List", 'OnAfterGetRecordEvent', '', false, false)]
    local procedure AfGetRecordItemList(var Rec: Record Item)
    begin
        StyleExprTxt := OurGlobalFunctions.ChangeItemColorAccordingToStock(Rec."No.");
    end;
    var
        OurGlobalFunctions: Codeunit "OurGlobalFunctions";
        [InDataSet]
        StyleExprTxt: Text[50];

But this -obviously- doesn’t work, as the “StyleExprTxt” variable is not passed by the procedure to the page extension that contains the modify(Description) part.
I’m missing a little something, but I can’t put my finger on it… Does anyone have an idea?
Thanks!