The sidebar is a list that show your recent activities within Tamago-DB. 

If the left sidebar is now showing, click on the gray tool "splitter" on the edge of page will toggle the sidebar visible/hidden.

Favorite / Sticky

You can favorite an activity by hovering over the space left of the activity title, a heart icon will appear, click on the icon to add the activity to the favorite list.

The favorited activity will show on top, even if you clear the activity history, the favorited activity will remain available.

To remove the item from your favorite list, click on the [heart icon] of the favorited item.

Hide the activity sidebar

If the sidebar is taking up too much space, you can hide it to increase the amount of space available in the main content panel.  Simply click on the "splitter" to hide the sidebar.