@Override
	public void setPositionManager(IPaintPositionManager manager) {
		fPaintPositionManager= manager;
	}
Returns the signed current selection. The length will be negative if the resulting selection
is right-to-left.
<p>
The selection offset is model based.
</p>

@param sourceViewer the source viewer
@return a region denoting the current signed selection, for a resulting RtoL selections
        length is < 0
@since 3.8
plugins/org.jkiss.dbeaver.ui.editors.sql/src/org/jkiss/dbeaver/ui/editors/sql/SQLMatchingCharacterPainter.java