Hi,
I’ve a suggestion! 
When e.g. fade in on a video track by the mouse<!>, I always have also for audio a FadeIn filter.
Is it possible to act on the kind of the track (audio / video), that e.g. I fade in on a video track only the video filter is set and not also the audio filter (and also for an audio track of course)?
TIA
Best regards
Earlybite
Of course you can uncheck ‘Audio fade-in’/’…out" in the ‘Filter’ section or delete it completely by pressing ‘-’ when highlighted.
Yes, I know, but I’m asking for to avoid that step… 
Because not always I remember it! And then I have filters in the project I’m not using…
No, this is rejected because a video track is actually an audio/video track. You can simply add the filters through the filter panel instead of using the fade control. Or, as @DvS said.
So it is possible to separate between audio - and video fade in/out…
And, you, as dev, knows on which track a user is working.
Sure, you can have a combined track with video and audio, but, and IMHO, mostly you have a separated source, only video or only audio, isn’t it?
If a user is working on a video track e.g., why not simply add only a video fade in/out?
And the using of the mouse to adjust the length of a fade in/out is more comfortable as with filter part, isn’t it?
And always you adjust with the mouse, let’s say for video, in the the time line, always a fade in/out for audio is added too…
If you ‘Detach Audio’ from your Video with audio source, then the fade-filters will only fade the layer ‘Video’ and only the detached layer ‘Audio’. So, you can fade these layers individually.
By the mouse in the time line? Really…?! Show me!
Here you are by ‘rightclick’ in the timeline for menu:
Of course ‘fade-out’, too!
Ok, there’s a bug that already existing ‘colorgrading’-filter copies in that detached audio. 
So I deleted it. (@shotcut)
Yes, I forgot that we do not automatically add the audio fade if the clip is made video only by disabling its audio track in Properties or Detach Audio as shown here (which disables the clip’s audio track for you). Yes, it is a minor bug that it copies video filters in the process of detaching, but it is rather harmless since the video filter will have no work to do on an audio-only clip.