vectorText could not update in a clean way

[yaozr]

I'd like to anmiate a vectortext with different text at different time, but when I update a previous drawn text, it seems some part of previous text remains on the 3d canvas. i.e. if you draw a "_" first and display, its done perfectly, if then draw a "v" using same vectorText in a second, most like you get a underscored v instead...

My understanding is vectorText is just a bunch of line element, so how to make sure when we reset the text attribute it will make a clean draw?

Any tips would be greatly appreciated!

Thanks in advance.