Always Skip doctests which depend on Qt and are in the class doc string

The doc test skip directive modifies the __doc__ attribute, which is not
possible for new-stlye classes.

skimage/viewer/plugins/base.py

@@ -16,7 +16,6 @@ else:
     has_qt = False
 
 
-@doctest_skip_parser
 class Plugin(QtGui.QDialog):
     """Base class for plugins that interact with an ImageViewer.
 
@@ -60,12 +59,12 @@ class Plugin(QtGui.QDialog):
     >>> from skimage import data
     >>>
     >>> plugin = Plugin(image_filter=lambda img,
-    ...                 threshold: img > threshold) # skip if not has_qt
-    >>> plugin += Slider('threshold', 0, 255)       # skip if not has_qt
+    ...                 threshold: img > threshold) # doctest: +SKIP
+    >>> plugin += Slider('threshold', 0, 255)       # doctest: +SKIP
     >>>
     >>> image = data.coins()
-    >>> viewer = ImageViewer(image) # skip if not has_qt
-    >>> viewer += plugin            # skip if not has_qt
+    >>> viewer = ImageViewer(image) # doctest: +SKIP
+    >>> viewer += plugin            # doctest: +SKIP
     >>> viewer.show()               # doctest: +SKIP
 
     The plugin will automatically delegate parameters to `image_filter` based

skimage/viewer/viewers/core.py

@@ -51,7 +51,6 @@ def mpl_image_to_rgba(mpl_image):
     return img_as_float(image)
 
 
-@doctest_skip_parser
 class ImageViewer(QtGui.QMainWindow):
     """Viewer for displaying images.
 
@@ -79,7 +78,7 @@ class ImageViewer(QtGui.QMainWindow):
     --------
     >>> from skimage import data
     >>> image = data.coins()
-    >>> viewer = ImageViewer(image) # skip if not has_qt
+    >>> viewer = ImageViewer(image) # doctest: +SKIP
     >>> viewer.show()               # doctest: +SKIP
 
     """