AEM 6.3 to 6.5 Upgrade - Custom Tab fields Issue in Page Properties

Hello Everyone,

We are upgrading to AEM 6.5 from AEM 6.3 - I am facing an issue with Dropdowns and DatePicker fields in custom tabs page properties[Touch UI]. I think this is not the issue with the any fields. Each Item is setting into fixed columns and when we try to open DatePicker or DropDown - Window is shrinking and show like below even though - we have more space on the window. I tried to build a new custom tab looking at the documentation - Still I am facing the same issue - I don't what has changed in AEM 6.5 on this - I see some depricated folders in foundation (granite/ui/components/coral/foundation/form/fieldset)

Here is xml for new tab:

               <testing_x0020_tab

                        cq:showOnCreate="true"

                        jcr:primaryType="nt:unstructured"

                        sling:resourceType="granite/ui/components/coral/foundation/fixedcolumns">

                        <items jcr:primaryType="nt:unstructured">

                            <column

                                jcr:primaryType="nt:unstructured"

                                sling:resourceType="granite/ui/components/coral/foundation/container">

                                <items jcr:primaryType="nt:unstructured">

                                    <section

                                        jcr:primaryType="nt:unstructured"

                                        sling:resourceType="granite/ui/components/coral/foundation/form/fieldset">

                                        <items jcr:primaryType="nt:unstructured">

                                            <dateAc

                                                jcr:primaryType="nt:unstructured"

                                                sling:resourceType="granite/ui/components/coral/foundation/form/fieldset">

                                                <items jcr:primaryType="nt:unstructured">

                                                    <datea

                                                        jcr:primaryType="nt:unstructured"

                                                        sling:resourceType="granite/ui/components/coral/foundation/form/datepicker"

                                                        displayedFormat="MMMM DD, YYYY hh:mm a"

                                                        fieldLabel="New T"

                                                        type="datetime"/>

                                                </items>

                                            </dateAc>

                                        </items>

                                    </section>

                                </items>

                            </column>

                        </items>

                    </testing_x0020_tab>

Can any please route me to any other options need to be changed?