I think I found a small bug in graphs drawing engine in OpenOffice 2.2 Calc
application.

When both primary and secondary grid is drawn for one value, the grid line looks
like the secondary grid, not like the primary grid.

Steps to reproduce the bug effect:
1. Create new spreadsheet with OOo Calc.
2. Create a simple data table:
x	y
1	600
2	800
3	1100
3. select all cells with data and insert a graph (using menu "Insert" ->
"Graph", ergo - using the wizard)
4. "Autoformatting the graph"(*) dialog window:
	4.1. (1st step) leave all as is, hit "next"
	4.2. (2nd step) Choose "XY graph" graph type; "data series in: columns", hit "next"
	4.3. (3rd) "grid lines" - select "Y axis"; click "Create"
5. right-click newly created graph, choose "edit" to open the graph edit mode
(all next steps will be done in this mode)
6. from "insert" menu choose "grids"
7. "Grids" window: select "Y axis" in "secondary grid" section; click "OK"
8. right-click somewhere in the graph area, from the context menu choose "axis"
and then "Y axis"
9. in "Y axis" dialog window:
	9.1. choose "scale" tab
	9.2. in section "scale axes" deselect "auto" in "minimum", "maximum", "main
range"(*), "secondary range"(*) (first 4 options)
	9.3. put your values in text fields which are now enabled - in "minimum": 0,
"maximum": 1500, "main range": 250, "secondary range": 100; (values are
important - I'll explain it later); hit "OK"
10. (optional) right-click somewhere in the graph area and choose "grids";
choose "main grid of Y axis"; make sure grid is "solid" and "black" (default
values); click "OK"
11. right-click somewhere in the graph area again, choose "grids" from the
context-menu again, but this time choose "secondary grid of Y axis"
12. we want secondary grid to be more "subtle" than main grid; choose "grey"
color, hit "OK"

The effect is that:
 - secondary horizontal grid lines are solid and grey
 - primary horizontal grid lines are solid black but not all(!)
 - primary grid lines which "collapse" with the secondary ones, are grey too(!)

For values of y, which are multiplies of 500, both primary and secondary grid is
drawn (this is what we needed the exact values of min/max and ranges in y axis
scale options). These grid lines look thiner/lighter - they are grey instead of
black. The should look like the primary grid lines (solid black), but they look
exactly like the secondary ones (solid grey).

It looks like for the values where both primary and secondary grid is drawn, the
"secondary grid" is drawn over the primary one - possibly it is drawn just after
the primary grid.

More:
 - The same problems appears in X grid.
 - The result are interesting when using "dashed" line style for one of prim/sec
grid also.
 - The unwanted effect is also visible in "print preview" mode (didn't print it
- I have no ink currently :P ).

(*) I've got polish (national language in Poland, code 'pl') version of
application, so original options/commands names can differ a little, sorry.