CategoryChart: How To suppress X Axis Text 9 out of 10 times?

In good (horrible) ol' ORACLE Grapics there was a pre-format-X-axis Value trigger. One could change the to_be_printed Text of the X-Axis Value on the fly, no side effects on the graph. Thus when rendering 365 Values (one per day) one could print Text in the X-Axis only for Mondays, thereby preventing cluttering and overwriting.

In FormSpider I tried a decode( mod( X, 10 ), 0 , X, NULL ) as X-Axis Column which nicely supressed the X Values that were not multiples of 10 but it also rendered only every 10th Value, thereby ruining the plot

I need a way to have points rendered, where the X-Axis doesn't print a value for. The decision to render a point should be independent from the contents of the Category column, at least for categoryCharts.

And while I'm at it, I'd like to control if a vertical grid line is drawn, maybe a drawXline_YN column, provided by my datasource may do that?

Come to think of it a printXValue_YN and printXvalueLine_YN control column would be the nicest, cleanest and most flexible solution