Mark output ws properties with existing ws names in algorithm dialogs

[mantid-builder]

Original Reporter: Arturs Bekasovs

Some users were complaining about the fact that currently it's too easy to accidentally overwrite a workspace when running algorithms using the GUI.

The most obvious solution here would be to show confirmations when we are about to overwrite something. However, in situations when we are experimenting with algorithm parameters and don't really care about whether previous output is overwritten, this can easily become irritating.

That's why, the proposed solution is as follows:

If the output workspace field references the workspace which already exists in the ADS, we mark that field somehow (e.g. change it's background color) so that the user is aware that this might cause data loss.

It should not be too bold to make user think that he is doing something wrong, yet noticeable enough to make people consider consequences before hitting Run.

Peter is currently doing lots of changes around that area, though we've decided that these ones are independent enough for me to be able to implement them myself.

[mantid-builder]

This issue was originally trac ticket 9161