Adding a "Deselect All" button so that you don't need to uncheck all other session in a multi-session environment every time you want to save three single-window session out of, say, 50 windows

src/pages/sessionManager.html

@@ -77,6 +77,7 @@
                 </div>
             </div>
             <div class="modal-footer align-right">
+                <button class="button-secondary" name="deselectAll">Deselect all</button>
                 <button class="button-secondary" name="closeSave">Close</button>
                 <button class="button-primary" name="save">OK</button>
             </div>