Merged in [16813] from rjsparks@nostrum.com:

    Don't offer to propose slides when the next view will not allow you to propose slides. Fixes ietf-tools#2763.
 - Legacy-Id: 16847
Note: SVN reference [16813] has been migrated to Git commit 1ec4f7f

Author: levkowetz

ietf/templates/meeting/session_details_panel.html

@@ -86,7 +86,7 @@ <h2 class="anchor-target" id="session_{{session.pk}}">{% if sessions|length > 1
         </table>
         {% if can_manage_materials %}
           <a id="uploadslides" class="btn btn-default pull-right" href="{% url 'ietf.meeting.views.upload_session_slides' session_id=session.pk num=session.meeting.number %}">Upload New Slides</a>
-        {% elif request.user.is_authenticated %}
+        {% elif request.user.is_authenticated and not session.is_material_submission_cutoff %}
           <a id="proposeslides" class="btn btn-default pull-right" href="{% url 'ietf.meeting.views.propose_session_slides' session_id=session.pk num=session.meeting.number %}">Propose Slides</a>
         {% endif %}
       </div>