A DESCRIPTION OF THE REQUEST :
in PrismTextLayout,

private float getTabAdvance() {
        float spaceAdvance = 0;
        if (spans != null) {
            /* Rich text case - use the first font (for now) */
            for (int i = 0; i < spans.length; i++) {
                TextSpan span = spans[i];
                PGFont font = (PGFont)span.getFont();
                if (font != null) {
                    FontStrike strike = font.getStrike(IDENTITY);
                    spaceAdvance = strike.getCharAdvance(' ');
                    break;
                }
            }
        } else {
            spaceAdvance = strike.getCharAdvance(' ');
        }
        return 8 * spaceAdvance;
    }


note the 8 * spaceAdvance, unable to be changed in runtime.

JUSTIFICATION :
Many text editors run a 4 * (width of space) so this can cause unintended graphical mistranslations when trying to upgrade software into JavaFX.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Some method e.g. TextLayout.setTabWidth() that allows us to modify the width of the tab, in spaces.
ACTUAL -
No such method provided; locked into using 8-width tabs

---------- BEGIN SOURCE ----------

TextFlow flow = new TextFlow();
flow.getChildren().add(new Text(" There is a tab before this text.\n There are four spaces before this text.\n There are eight spaces before this text"));

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
n/a, security privileges prevent injecting code into the JRE. The only option is to render tabs by converting tabs into a series of spaces but this is difficult to implement.