QText2DEntity width computed by QFontMetricsF is too small

When using multiple subsequent spaces in a string the width calculated by QFontMetrics::boundingRect is too small to fit the entire string on one line for a QText2DEntity. QText2DEntity inserts a line break and draws the fps number on the next line. If I remove all spaces (the one after the colon and the padding) the string is properly drawn on a single line. The error seems to be that the 3D text rendering requires more horizontal space than the 2D font rendering.