I want to share a little bit of tips here since some people in the community were asking about it. Normally, we cant add any buttons inside Action Bar. We also cant add custom icons in the buttons.
Note that this is a tips for beginner and not for those folks that clearly much more experienced than me.
Here are the steps :
Hide the default Action Bar
By unchecking Title Visible on Screen Properties
Add A New Action Bar
By adding a new horizontal layout with any colors that you like. Set properties to your liking. Below is an example.
Add A Shadow or Border
By adding a new horizontal layout with darker or lighter color (depend on the Action Bar color) as a shadow or as a border. Set it’s Height to 2 px. Below is an example of the visual.
Add Context Menu
By adding a new label, use above font. On the Text Properties type : 
Add trigger to show context menu by using below blocks.
If you dont understand how to set Menu Item see here : About This Application Screen
Below is the result.
And when you press menu :
NB : You can even add a search bar by adding a TextBox component. Set its background color same as ActionBar color. You can set it hidden by default and when certain button pressed, it can show up and automatically focused by using below blocks. Dont forget to add KitchenSink component.