I imported a drawing in white text on black background. I want black text on white background.
Help?

1 – Draw a BLACK rectangle the same size as the imported drawing.

2 – move the rectangle drawn so it covers your imported drawing, then press Page Down to Make sure the imported drawing IS      the layer on top

3 – Select your imported drawing then hold shift key down and select the black rectangle you drew.

4 – From the top menu select Object->Mask->Set You will have all your white text now in black on a white back ground.

Source: Question #124157 : Questions : Inkscape