Bug 47499 Quick Diff hovers don't use text editor font
Quick Diff difference hovers use the java editor's text font for hovers to provide an easy "visual diff" by hovering/unhovering. This doesn't work in *text* editors (e.g. on a *.properties file), since the hover uses a default font and doesn't take over the text editor's.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/JavaChangeHover.java
public JavaChangeHover(String partitioning) {
		fPartitioning= partitioning;
	}
	
	/*
	 * @see org.eclipse.ui.internal.editors.text.LineChangeHover#formatSource(java.lang.String)
	 */
	protected String formatSource(String content) {
		return content;
	}
	
	/*
	 * @see org.eclipse.jface.text.source.IAnnotationHoverExtension#getHoverControlCreator()
	 */
	public IInformationControlCreator getHoverControlCreator() {
		return new IInformationControlCreator() {
			public IInformationControl createInformationControl(Shell parent) {
				fInformationControl= new CustomSourceInformationControl(parent, fPartition);
				return fInformationControl;
			}
		};
	}
	
	/*
	 * @see org.eclipse.jface.text.source.LineChangeHover#computeLineRange(org.eclipse.jface.text.source.ISourceViewer, int, int, int)
	 */
	protected Point computeLineRange(ISourceViewer viewer, int line, int first, int number) {
		Point lineRange= super.computeLineRange(viewer, line, first, number);
		if (lineRange != null) {
			fPartition= getPartition(viewer, lineRange.x);