added a feature which brings up a error message box, if there was any issue with the msr-file when starting musrview from musredit.

src/include/PMsrHandler.h

@@ -31,6 +31,8 @@
 #define _PMSRHANDLER_H_
 
 #include <memory>
+#include <sstream>
+#include <string>
 
 #include <TString.h>
 #include <TComplex.h>
@@ -102,6 +104,8 @@ class PMsrHandler
 
     virtual void GetGroupingString(Int_t runNo, TString detector, TString &groupingStr);
     virtual Bool_t EstimateN0();
+    
+    virtual std::string GetLastErrorMsg() { return fLastErrorMsg.str(); }
 
   private:
     Bool_t                 fFourierOnly; ///< flag indicating if Fourier transform only is wished. If yes, some part of the msr-file blocks are not needed.
@@ -128,6 +132,8 @@ class PMsrHandler
 
     Bool_t fCopyStatisticsBlock; ///< flag, if true: just copy to old statistics block (musrt0), otherwise write a new one (musrfit)
 
+    std::stringstream fLastErrorMsg;
+
     virtual Bool_t HandleFitParameterEntry(PMsrLines &line);
     virtual Bool_t HandleTheoryEntry(PMsrLines &line);
     virtual Bool_t HandleFunctionsEntry(PMsrLines &line);