Only show changelog if we have a global container stack

If we have no global stack we can assume this is a "first run"
situation.

Contributes to CURA-2519

plugins/ChangeLogPlugin/ChangeLog.py

@@ -33,7 +33,6 @@ class ChangeLog(Extension, QObject,):
         Application.getInstance().engineCreatedSignal.connect(self._onEngineCreated)
         Preferences.getInstance().addPreference("general/latest_version_changelog_shown", "2.0.0") #First version of CURA with uranium
         self.addMenuItem(catalog.i18nc("@item:inmenu", "Show Changelog"), self.showChangelog)
-        #self.showChangelog()
 
     def getChangeLogs(self):
         if not self._change_logs:
@@ -87,6 +86,13 @@ class ChangeLog(Extension, QObject,):
         else:
             latest_version_shown = Version(Preferences.getInstance().getValue("general/latest_version_changelog_shown"))
 
+        Preferences.getInstance().setValue("general/latest_version_changelog_shown", Application.getInstance().getVersion())
+
+        # Do not show the changelog when there is no global container stack
+        # This implies we are running Cura for the first time.
+        if not Application.getInstance().getGlobalContainerStack():
+            return
+
         if self._version > latest_version_shown:
             self.showChangelog()
 
@@ -95,7 +101,6 @@ class ChangeLog(Extension, QObject,):
             self.createChangelogWindow()
 
         self._changelog_window.show()
-        Preferences.getInstance().setValue("general/latest_version_changelog_shown", Application.getInstance().getVersion())
 
     def hideChangelog(self):
         if self._changelog_window: