Really nice, I like it. Just few things I would like to suggest. 
When we enter name of object how about that, if we could select the object from available objects in our project?
It would make it easier and faster. Probably everybody know the name of the objects using in the project, but it would be nice to have anyway especially on touch screen devices (I don’t like to type on touch screen 
).
Also how about that if the key and mouse press conditions could be added to customization options in case the user prefer to use different keys?
For example in the move an object left,right… event we using the arrow keys but normally I would prefer wasd. So the users could edit also if they want to use key, any key or mouse, if key what key if mouse, which button just like in the events. Of course not a big deal to find these events and change it there, but still would be nice to have it as a customization option.
And then, how about a yes/no customization option?
Basically it would be a variable used in events similar to boolean true/false to let users to activate/deactivate different parts/functions of the event. For example to let users to choose if they want object to rotate or not. Technically I can let users to choose by using a variable. if rotate = 1 object rotate, if rotate = 0 object don’t rotate and as a customization option user can enter manually 1 or 0 in case of a string variable enter manually “yes” or “no”. But would be more practical to be able to choose from a drop down list if yes or no, so it would be basically a variable type which could have only 2 possible value yes or no and if we add it as a customization option, the user could choose from a drop down list yes or no. Would be even better if we could add any and as many option to choose from we want to make it even flexible the use for example to let user to choose if it green, yellow, or black, left or right, male or female, top or bottom, we could add any option we want (predefine possible values basically) and the users could choose from them in the customization menu. But to have a yes/no option to choose from would be a nice start.
By using such features for example in my shooting bullets event which is at the moment just start shooting bullets right from the start care about nothing so not very practical, the user could choose from definite options, if he/she want to use a key or mouse to be pressed to shoot bullets or not, if yes then which key or mouse button and even choose type of shoot like to be fast as a rifle or slow as a rocket launcher and to shoot bullets from position of specified object or not if yes object can be choose from the list if not then X,Y coordinates can be entered and such. So this way events could be designed to be editable, customizable with minimal knowledge and understanding of events and expressions at really advanced level in a practical way.
Also, when we deactivate a group or any event inside the group, I think the group should change it colour to be clearly visible if anything is deactivated inside the group and when we insert an event, would be nice to have an “x” in the corner or a “cancel” option in case we have changed our mind and this way we can get back to our events quickly. And the same when we open to edit a group but changed our mind later 
):