Remove Gap of a Cell inside AdvancedDataGrid

I created an item renderer for a advanced datagrid and decided to put color on some of the cells. However the result comes with a vertical gap between the colored cell ( you can notice a big gap of white lines between the red cells on the screenshot)

Any idea how to remove this?

For the coloring of cell, I follow this tut开发者_如何学JAVAorial link.

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Can you set paddingBottom and paddingTop to 0? Docs make me think that these two properties control the gap.

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What happens if you try replacing g.drawRect(0, 0, unscaledWidth, unscaledHeight) with g.drawRect(0, -2, unscaledWidth, unscaledHeight+3)?