Resolves: tdf#123694 we need the controller, not the tabpage parent

Change-Id: Ib390abaec648a1e06fcc35f83cb170fc654cf021
Reviewed-on: https://gerrit.libreoffice.org/69203
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
diff --git a/chart2/source/controller/dialogs/res_ErrorBar.cxx b/chart2/source/controller/dialogs/res_ErrorBar.cxx
index 8d0517c..3de8249 100644
--- a/chart2/source/controller/dialogs/res_ErrorBar.cxx
+++ b/chart2/source/controller/dialogs/res_ErrorBar.cxx
@@ -41,8 +41,9 @@ namespace
{
void lcl_enableRangeChoosing(bool bEnable, TabPageParent pParent)
{
    if (weld::Window* pWeldDialog = dynamic_cast<weld::Window*>(pParent.pPage))
    if (weld::DialogController* pController = pParent.pController)
    {
        weld::Window* pWeldDialog = pController->getDialog();
        pWeldDialog->set_modal(!bEnable);
        pWeldDialog->show(!bEnable);
    }