You used to be able to manually specify values when the input dataset was not yet ready.
Example:
tabular.Group tool.The user was previously presented with a text box to allow manual entry.
ping @guerler
Bumped into this issue again, but searched before creating a new one...

And again....

This is a major show-stopper. And it totally used to work.
Being able to actually queue up analysis steps is a major component of Galaxy.
I just want to sort on column 2, but will have to come back in a few hours to run the tool....

Reopening issue. There is a hack fix for the columns option, that doesn't really solve this issue for column parameters.
Furthermore, this issue is for all dynamically generated parameter values. For example, I can no longer select the species from a MAF dataset. In this case history item 3 is still being generated, and there should be a text box to allow manually entering species:
