With javafx.scene.web.WebView, when the letter is the surrogate pair character (ex: CJK Unified Ideographs Extension B), the program could not render that.

for example:
U+4E00 (CJK Unified Ideographs)
<span style="font-family:SimSun-ExtB;">&#x4e00;</span>
... OK on usual browser
... OK on WebView
U+20000 (CJK Unified Ideographs Extension B) == D840+DC00
<span style="font-family:SimSun-ExtB;">&#x20000;</span>
... OK on usual browser
... NotGood on WebView
<span style="font-family:SimSun-ExtB;">&#xd840;&#xdc00;</span>
... OK on usual browser
... two ? glyphs on WebView

When NotGood, NullPointerException has occurred:
java.lang.NullPointerException
at com.sun.t2k.T2KFontFactory.getFontResourceByFileName(T2KFontFactory.java:482)
at com.sun.t2k.T2KFontFactory.getFontResource(T2KFontFactory.java:420)
at com.sun.t2k.FallbackResource.getSlotResource(FallbackResource.java:168)
at com.sun.t2k.T2KCompositeFontResource.getSlotResource(T2KCompositeFontResource.java:50)
at com.sun.t2k.CompositeGlyphMapper.getSlotMapper(CompositeGlyphMapper.java:52)
at com.sun.t2k.CompositeGlyphMapper.convertToGlyph(CompositeGlyphMapper.java:73)
at com.sun.t2k.CompositeGlyphMapper.getGlyphCode(CompositeGlyphMapper.java:129)
at com.sun.t2k.CharToGlyphMapper.charToGlyph(CharToGlyphMapper.java:116)
at com.sun.t2k.CompositeStrike.getCharAdvance(CompositeStrike.java:183)
at com.sun.webpane.sg.prism.WCFontImpl.getGlyphWidth(WCFontImpl.java:140)
at com.sun.webpane.webkit.Timer.twkFireTimerEvent(Native Method)
at com.sun.webpane.webkit.Timer.fireTimerEvent(Timer.java:66)
at com.sun.webpane.webkit.Timer.notifyTick(Timer.java:47)
at javafx.scene.web.WebEngine$PulseTimer$2.pulse(WebEngine.java:586)
at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:292)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:385)
at com.sun.javafx.tk.quantum.QuantumToolkit$8.run(QuantumToolkit.java:311)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$2$1.run(WinApplication.java:62)
at java.lang.Thread.run(Unknown Source)