I myself would love some quality of life improvements on the UI itself, including the ability to see on the scrollbar where results of the search are located at and/or the results are highlighted.
Ability to have an option to do a global search of all event sheets to see where a variable/search result is used/located.
Other than that, I have nothing to add to the discussion.
Basically, and I want to direct this to 
Ashley too, we all would welcome more practical stuff, that would make work easier and faster, more intuitive if you like, but also more flexible at places. Take triggers for example: they are grate, but having no ability to set a delay, makes for less smooth gameplay - sometimes you need that extra milliseconds to tighten things up. You can make a work-around with timer, but that means there is at lease several more events there to do per object type. And Imagine making a sequential movements, like for elevators or spikes. There is no way of grouping objects on the go, other then trough building up trees of events. Or Or even such simple thing like keys bindings. Work-arounds pile up and not always work great. So I'd really like to ask you to consider having events expanded, by thinking of more possible scenarios.
As for editor, streamlined navigation will be nice, rulers would be nice, drawing masks, as well as collision masks in the editor itself would be great too. Ability to zoom preview animations is needed for low res games. Having easier way of managing object's variables is really needed thought - sometime's those variables are need to be used for long sentences of tokens. And speaking of sentences a proper text editing would be great too. There is panty of things to improve. maybe hireing a ux person with gaming background would help? Cause we need to stop with finding work-rounds; there is other software i use where there is a need to find a work arounds constantly. It takes away mountains from actual workflow.
Also, as a side note, there is a problem with large arrays: they don't seam to be able to finish loops in a single pass. Sometimes it is needed to create a set of events that will select an area of the array before moving on to next one in the next tick, and this way it works faster! So I thought I'll mention that.