Do you know of any aesthetically-pleasing and effective ways of indicating that a table's contents have been filtered, without the filter information getting in the way?
Some background on my particular app...
Background
We've got data tables throughout our app -- sometimes, more than one per screen -- and each of these tables can be filtered independently. That is, the user can set up a filter to show/hide rows based on categories they've assigned to the row items e.g. show all items categorised as both 'important' and 'mine' unless they've also been categorised as 'old'.
Due to the flexibility and complexity of the filters, they're set up in a separate, modal dialog, which has room for in-place help. We simply can't afford to use up valuable real estate by having the filtering options permanently visible. It would add significantly to visual clutter.
Problem
All of this stuff works, but we've found that people sometimes forget they've got a filter applied and then make decisions / take actions based on false assumptions about their data. To prevent this, we figure we need to indicate that the user may not be looking at their full data set (when a filter's applied). But, as stated earlier, we really can't afford to clutter the screen with the details of the filter itself.
Our current implementation
For the record, here's the UI we currently have:
It's the "Tag filter applied" panel, btw, not the text-box to the right as well. It's cumbersome, to say the least.
Examples in the wild
The only example of this kind of UI that I can recall is in Microsoft Outlook 2003(?). They had a rather poor implementation, in which the status bar simply held a bit of text saying "Filter applied". This was practically invisible to most people, so wouldn't address the problem. I guess MS got away with it because, in their case, people rarely edited the filter, which isn't the case for my users.
Do you know of any better examples? Or do you have any good ideas of your own?