Hi Ivan,
Greetings from Syncfusion, we have analyzed your query and we like to let you know that the we are currently working on this feature and it will be available in our upcoming Volume 3 release which is scheduled to be rolled out at the end of September 2018. We appreciate your patience until then.
The current behavior of shape selection and deselection behaves like this, if you select a particular area it selects, if you want to deselect the area, you need to click on the same area again. So, in the upcoming feature we will provide a boolean property to show that the shape is selected or not when clicking on the shapes and the event will fire for de-selection as well.
Thanks,
Michael