I am trying to process with Proguard a MS Windows desktop application (Java 6 SE using the SWT lib provided by Eclipse). And I get the following critical error:

```
Unexpected error while performing partial evaluation:
Class = [org/eclipse/swt/widgets/DateTime]
Method = [<init>(Lorg/eclipse/swt/widgets/Composite;I)V]
Exception = [java.lang.IllegalArgumentException] (Can't find common super class of [java/lang/StringBuffer] and [org/eclipse/swt/internal/win32/TCHAR])
Error: Can't find common super class of [java/lang/StringBuffer] and [org/eclipse/swt/internal/win32/TCHAR]
----------------------------

```

When I tried to Google the error, it came out only on two spots on the entire web, that astonished me greatly.
I am newbie using Proguard and Java code optimization tools at all.
Any thoughts and suggestions how to fix this, will be appreciated. Thanks in advance.

**Above error is now fixed,** with the using of "-dontskipnonpubliclibraryclasses"

**--final update:**

I still get another error now.
The whole output is now the folowing:

```
D:\eclipse_projs\java_obfuscate\gci>gci.bat
ProGuard, version 4.4
Reading program jar [D:\eclipse_projs\java_obfuscate\gci\gci.jar]
Reading library jar [D:\jre1.6.0_07\lib\rt.jar]
Unexpected error while evaluating instruction:
  Class       = [org/eclipse/swt/widgets/Synchronizer]
  Method      = [runAsyncMessages(Z)Z]
  Instruction = [60] aload_1 v1
  Exception   = [java.lang.IllegalArgumentException] (Value is not a reference value [proguard.evaluation.value.UnknownIntegerValue])
Unexpected error while performing partial evaluation:
  Class       = [org/eclipse/swt/widgets/Synchronizer]
  Method      = [runAsyncMessages(Z)Z]
  Exception   = [java.lang.IllegalArgumentException] (Value is not a reference value [proguard.evaluation.value.UnknownIntegerValue])
 Error: Value is not a reference value [proguard.evaluation.value.UnknownIntegerValue]

D:\eclipse_projs\java_obfuscate\gci>

```

This is a problem that i cannot understand for certain :( any help will be much appreciated.

The options I use are the following:

```
-dontskipnonpubliclibraryclasses
-dontskipnonpubliclibraryclassmembers
-optimizationpasses 3
-overloadaggressively
-repackageclasses ''
-allowaccessmodification
-dontnote

```