Once a tabular data result is available in Firefly, there are currently several ways to apply filters to the resulting data.  Notably:

• One can enable the column-filtering table header, and type in expressions there like "< 3.6".
• One can open the column-metadata dialog in the table viewer, which displays information about each column in the data table as a row in the dialog, and includes a field in each row for applying a column filter - and displays any existing column filters applied via the table header.
• One can apply a free-form set of filter expressions in a field at the bottom of the column-metadata dialog.
• One can select regions of data in an x-y plot and then request that that selection be used as a filter.  For a rectangular region x_min, x_max},{y_min, y_max this results in the application of two filters to each of the columns x and y.
• One can view the column filters from the "show filters" button on an X-Y plot. (Not any more, 6/27/18 XW)
• In the resulting dialog, one can apply a free-form filter expression.

There are aspects of this that are not implemented uniformly across the different types of filter.  This ticket asks that these be changed to increase the uniformity and orthogonality of the user experience of filtering.

In particular:

• The dialog box for column metadata is accessed via the "gears" icon on tables but via the "funnel" icon on plots.  While I understand the motivations that led to this (e.g., "gears" is an appropriate concept for the choose-which-columns-to-display function of the dialog that appears for tables, and is parallel to the choose-columns-to-plot concept that the plot viewer's "gears" brings up), the net result is a problematic UX for "show me the filters that are currently in place".  I do not have an immediate suggestion for what to do about this.
• The dialog boxes that appear are close in appearance, but still differ in ways that go beyond the fact that the one opened by the "gears" icon on tables has the additional functions of column selection and control of units/filter display in the main table.  For instance, the table-"gears" one can be dismissed by an "x" in the upper right, while the plot-"funnel" one can only be dismissed by clicking on the funnel again.  Also, only the table-"gears" one has the "Reset" action available.
  • Note also that the "Reset" action is drawn as a link (blue text) whereas the "Reset" on the plot-options dialog is a button.  But the plot-options dialog is a matter for another day.
• Plot selections via drawn rectangles allow their use for either row selection or filtering depending on whether the "check" or "funnel" action icon is selected.  Column-header (and column dialog) selections can only be used for filtering.  This is a serious break of orthogonality and is actively frustrating when doing exploratory data analysis.  It is very useful to be able to set up an x-y plot and then mark a subset of the points in the plot based on an additional selection predicate.  (This is not to be confused with the similar capability of coloring points, or changing their plot symbol, based on values of additional columns.)  I don't have an immediate suggestion for the UI for switching between selection and filtering based on a column predicate, but I believe this is a very important point to address and I'll think about it more.