Galaxy: Display output labels in workflow editor

[mvdbeek]

from @mblue9 in https://github.com/galaxyproject/tools-iuc/pull/2103#issuecomment-424235825

I received some user feedback that in the editor view the featurecounts outputs are a bit confusing, see below (e.g. it's not very obvious to users what output_short, output_medium and output_full are).

This should be straightforward, we can display the label (maybe on hover, to not cram too much text in there ?)

[mblue9]

Displaying the labels would be really great (if that's possible)!

[mvdbeek]

As usual I haven't thought about this enough. Many tools use cheetah to fill in a couple of things, this is most of the time {on_string} and/or {tool.name}. We could try to fill those in using cheetah, but we'd probably miss some of the more extravagant labels like ${input.name} (as BAM). A quick grep through the IUC tells me this isn't used a lot and would probably improve the situation for 95% of the tools. Or we just display the label as it is defined in the xml (${tool.name} on ${on_string}: junction counts) for the featureCounts example.

[mvdbeek]

I made some progress on this, I think this is actually feasible if we replace on_string with input dataset(s):

Concatenate datasets here doesn't have a label, but the others do.
This is from https://github.com/mvdbeek/galaxy/commit/4cdd0774c5fd5b9a1eaafe034ae1c20c077abf92 -- Just need to figure out what to do with the actual variable name. We have to display it somewhere so that the rename actions make sense.

[mvdbeek]

I think I got this right now, and in addition I'm also displaying the available inputs as a list, with the variable name in bold and the label as you see it in the editor next to it -- that should hopefully make things easier: