Platform.haveGui is only true if a wx.App is running. New

Platform.canHaveGui, can be used to tell whether we are able to create a
GUI. Async modified to use platform.haveGui instead of performing its
own test.

fsl/utils/async.py

@@ -88,13 +88,8 @@ def _haveWX():
     """Returns ``True`` if we are running within a ``wx`` application,
     ``False`` otherwise.
     """
-    
-    try:
-        import wx
-        return wx.GetApp() is not None
-    
-    except ImportError:
-        return False
+    import fsl.utils.platform as fslplatform
+    return fslplatform.platform.haveGui
 
 
 def run(task, onFinish=None, onError=None, name=None):

fsl/utils/platform.py

@@ -79,6 +79,7 @@ class Platform(notifier.Notifier):
        frozen
        fsldir
        haveGui
+       canHaveGui
        inSSHSession
        wxPlatform
        wxFlavour
@@ -100,6 +101,7 @@ class Platform(notifier.Notifier):
 
         self.__fsldir       = os.environ.get('FSLDIR', None)
         self.__haveGui      = False
+        self.__canHaveGui   = False
         self.__inSSHSession = False
         self.__wxFlavour    = None
         self.__wxPlatform   = None
@@ -107,8 +109,13 @@ class Platform(notifier.Notifier):
         self.__glRenderer   = None
 
         try:
+
             import wx
-            self.__haveGui = True
+
+            self.__canHaveGui = True
+            
+            if wx.GetApp() is not None:
+                self.__haveGui = True
 
         except ImportError:
             pass
@@ -168,6 +175,12 @@ class Platform(notifier.Notifier):
         return self.__haveGui
 
 
+    @property
+    def canHaveGui(self):
+        """``True`` if it is possible to create a GUI, ``False`` otherwise. """
+        return self.__canHaveGui
+
+
     @property
     def inSSHSession(self):
         """``True`` if this application is running over an SSH session,