The value of STRING is #(71 85 73 32 68 101 109
                         111), which is not of type STRING.
   [Condition of type SIMPLE-TYPE-ERROR]

Restarts:
 0: [STORE-VALUE] Supply a new value for STRING.
 1: [RETRY] Retry SLIME REPL evaluation request.
 2: [ABORT] Return to SLIME's top level.
 3: [TERMINATE-THREAD] Terminate this thread (#<THREAD "repl-thread" RUNNING {B044AE9}>)

Backtrace:
  0: (SB-KERNEL:CHECK-TYPE-ERROR STRING #(71 85 73 32 68 101 ...) STRING NIL)
  1: (CFFI:FOREIGN-STRING-ALLOC #(71 85 73 32 68 101 ...))[:EXTERNAL]
  2: (GTK-FFI::GTK_WINDOW_SET_TITLE #.(SB-SYS:INT-SAP #X080AA558) #(71 85 73 32 68 101 ...))
  3: (GTK-FFI:GTK-WINDOW-SET-TITLE #.(SB-SYS:INT-SAP #X080AA558) "GUI Demo")
  4: ((LAMBDA (SB-PCL::.PV. SB-PCL::.NEXT-METHOD-CALL. SB-PCL::.ARG0. SB-PCL::.ARG1. SB-PCL::.ARG2. SB-PCL::.ARG3. SB-PCL::.ARG4. SB-PCL::.ARG5.)) ..)
  5: ((SB-PCL::FAST-METHOD CELLS:MD-AWAKEN (CELLS::MODEL-OBJECT)) #<unavailable argument> #<unavailable argument> TEST-GUI)
  6: ((LAMBDA (SB-PCL::.PV. SB-PCL::.NEXT-METHOD-CALL. SB-PCL::.ARG0.)) #<unavailable argument> #<unavailable argument> TEST-GUI)
  7: ((SB-PCL::FAST-METHOD CELLS:MD-AWAKEN :AROUND (CELLS::MODEL-OBJECT)) ..)
  8: (CELLS::CALL-WITH-INTEGRITY :AWAKEN TEST-GUI #<CLOSURE (LAMBDA #) {ACC1515}> #<unavailable argument>)
  9: ((LAMBDA (SB-PCL::.PV. SB-PCL::.NEXT-METHOD-CALL. SB-PCL::.ARG0. SB-PCL::.ARG1. SB-INT:&MORE SB-PCL::.DFUN-MORE-CONTEXT. SB-PCL::.DFUN-MORE-COUNT.)) ..)
 10: ((SB-PCL::FAST-METHOD SHARED-INITIALIZE :AROUND (CELLS:MODEL T)) ..)[:EXTERNAL]
 11: ((LAMBDA (SB-PCL::.PV. SB-PCL::.NEXT-METHOD-CALL. SB-PCL::.ARG0. SB-INT:&MORE SB-PCL::.DFUN-MORE-CONTEXT. SB-PCL::.DFUN-MORE-COUNT.)) #<unused argument> #<unused argument> TEST-GUI -310034821 26)
 12: ((SB-PCL::FAST-METHOD MAKE-INSTANCE (CLASS)) #<unavailable argument> #<unavailable argument> #<STANDARD-CLASS CL-MDM-GUI::TEST-GUI>)[:EXTERNAL]
 13: (CELLS-GTK::SHOW-WIN CL-MDM-GUI::TEST-GUI)[:EXTERNAL]
 14: (CELLS-GTK:START-APP CL-MDM-GUI::TEST-GUI)[:EXTERNAL]
 15: (SB-INT:SIMPLE-EVAL-IN-LEXENV (CL-MDM-GUI:GUI-DEMO) #<NULL-LEXENV>)
 --more--