只要编辑文本域，就会出现这个报错，然后连带着按钮，开关，I/O域反正除了图形之外都会消失。

这是针对 WinCC flexible 工程设计系统自动生成的错误报告。

 Professional 6.2.9200.0

产品版本: WinCC flexible SMART V3 SP2; V 3.00 ServicePack 2; V 3.0 SP 2.0 (7.10.10)

System.ArgumentNullException

键不能为 null。

参数名: key

Exception Source 

mscorlib

Exception Target Site

System.Object get_Item(System.Object)

Exception Stack Trace

   在 System.Collections.Hashtable.get_Item(Object key)

   在 Siemens.Simatic.Hmi.Utah.Common.Services.NearestFontCache.GetNearestFont(IHmiObject device, String languageName, Font inputFont)

   在 Siemens.Simatic.Hmi.Utah.Common.Services.FontService._GetNearestFont(String languageName, IHmiObject iHmiObject, Font font, Boolean& isDifferent)

   在 Siemens.Simatic.Hmi.Utah.Common.Services.FontService.Siemens.Simatic.Hmi.Utah.Common.Services.IDeviceFontService.GetNearestFont(String languageName, IHmiObject iHmiObject, Font font)

   在 Siemens.Simatic.Hmi.Utah.Text.HmiText.MaxSize(Graphics graphics, HmiObjectHandle hmiFontListHandle, Boolean windowsCE, Boolean bMultiline)

   在 Siemens.Simatic.Hmi.Utah.Text.HmiText.MaxSize(Graphics graphics, HmiObjectHandle hmiFontListHandle, Boolean windowsCE)

   在 Siemens.Simatic.Hmi.Utah.GraphX.HmiTextField.AdjustBoundsOnText()

   在 Siemens.Simatic.Hmi.Utah.GraphX.HmiTextField.set_Size(Size value)

   在 Siemens.Simatic.Hmi.Utah.GraphX.HmiScreenItem.SetScreenItemProperty(String propertyName, Object value, Boolean ex)

   在 Siemens.Simatic.Hmi.Utah.GraphX.HmiScreenItem.Siemens.Simatic.Hmi.Utah.Common.Base.IPropertyTable.set_Item(String propertyName, Object value)

   在 Siemens.Simatic.Hmi.Utah.GraphX.TextField.UpdateFieldOnObjectChange(IHmiObject hmiobject)

End Exception