Get actual MinorStep (or any grid-related values)

Dear oxyplotters,
I am trying to create plot containing both Carthesian and Polar grid. For the first one I use regular Major- nad MinorGridLines, whereas for the second one I intended to use EllipseAnnotations. Now everyting would be fine, if only I could get the actual Major- or MinorStep, the problem is that both are either zero or NaN. Any hints on what can I do?
Regards,
Bolek

Maybe you are querying the properties too early. The ActualMajorStep/ActualMinorStep properties are set when the plot is being updated/redrawn. The values of these properties depends on the width/height of the plot.