fpspreadsheet: Fix occasionally incorrect width of row header column in TsWorksheetGrid

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@3934 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpspreadsheet/fpspreadsheetgrid.pas

@@ -3406,6 +3406,7 @@ begin
     FixedCols := FFrozenCols + FHeaderCount;
     FixedRows := FFrozenRows + FHeaderCount;
     if ShowHeaders then begin
+      Canvas.Font.Assign(Font);
       ColWidths[0] := Canvas.TextWidth(' 999999 ');
       RowHeights[0] := DefaultRowHeight;
     end;