Re #5366. Ability to connect not checked in validateInputs().

Repeatedly connecting/disconnecting every time validateInputs was
called is undesirable. We can now create a listener without
connecting (#6553), so we can still check whether this is asking to
add histograms together.

Code/Mantid/Framework/DataHandling/src/LiveDataAlgorithm.cpp

@@ -287,16 +287,10 @@ namespace DataHandling
     std::map<std::string, std::string> out;
 
     const std::string instrument = getPropertyValue("Instrument");
-    try {
-      const bool eventListener = LiveListenerFactory::Instance().create(instrument,false)->buffersEvents();
-      if ( !eventListener && getPropertyValue("AccumulationMethod") == "Add" )
-      {
-        out["AccumulationMethod"] = "The " + instrument + " live stream produces histograms. Add is not a sensible accumulation method.";
-      }
-    }
-    catch ( std::runtime_error& )
+    const bool eventListener = LiveListenerFactory::Instance().create(instrument,false)->buffersEvents();
+    if ( !eventListener && getPropertyValue("AccumulationMethod") == "Add" )
     {
-      out["Instrument"] = "Unable to connect to live stream for " + instrument;
+      out["AccumulationMethod"] = "The " + instrument + " live stream produces histograms. Add is not a sensible accumulation method.";
     }
 
     if (this->getPropertyValue("OutputWorkspace").empty())

Code/Mantid/Framework/DataHandling/test/LiveDataAlgorithmTest.h

@@ -71,7 +71,6 @@ class LiveDataAlgorithmTest : public CxxTest::TestSuite
     TS_ASSERT( alg.isInitialized() )
     TS_ASSERT( !alg.hasPostProcessing() );
 
-    TSM_ASSERT("Can't connect", !alg.validateInputs()["Instrument"].empty() );
     alg.setPropertyValue("Instrument","FakeEventDataListener");
 
     TSM_ASSERT("No OutputWorkspace",  !alg.validateInputs()["OutputWorkspace"].empty() );

Code/Mantid/MantidQt/CustomDialogs/src/StartLiveDataDialog.cpp

@@ -99,7 +99,6 @@ void StartLiveDataDialog::initLayout()
 
   // ========== Set previous values from history =============
   fillAndSetComboBox("Instrument", ui.cmbInstrument);
-  tie(ui.cmbInstrument, "Instrument", ui.horizontalLayout_5);
   tie(ui.edtUpdateEvery, "UpdateEvery", ui.layoutUpdateEvery);
   fillAndSetComboBox("AccumulationMethod", ui.cmbAccumulationMethod);