Reject wrong workspace URL when creating a new one

[renyuneyun]

When you create some "stuff" on Mashlib, it often requires a "workspace" to store the data.
Normally, you also create your workspace on the same UI -- I did not find a different place to do this.

When creating the workspace, you need to specify the URL of your workspace.
It currently accepts anything (as far as I tried), so it gave me the impression that it can automatically resolve relative paths.
However, in fact, when creating the "stuff", it will reject such scenarios, and reminds you that only absolute URIs/URLs are accepted.

It would be ideal if validating/checking and alerting happens when creating the workspace. If not totally possible, it should at least reject the obviously wrong ones (e.g. relative paths; non-URLs).