Suggestion: Event Handler improvements

Hi Guys,

The Event Handler adds the new events to the end of the list.

It can be very useful to add a new line to the current position with a key combination. Moving with buttons has some difficulties for a long list. For example, pressing only the + sign can add the end of the list, and with CTRL can the current position.

If there is already this kind of feature I couldn't find it in the documents.

In addition, some key combinations for collapsing the tree to first, second ... levels is also can be useful. For example CTRL + left arrow for collapsing and CTRL + right arrow for expanding can be used.

We may probably change the way events are added in Radzen 3.