Don't crash when the vigil window is made very small.

This is a workaround, not being able to get very small appearances is still
there. For now the main appearance won't shrink below a width of 10
or a height of 20, but thats okay since the interface is already impractical
at that point. The minimum appearance is then cropped to fit the window.

BUGS

@@ -5,7 +5,6 @@ Current
   e.g. vigil.py pylint, BUGS metadata, BUGS _pygments
 - Scrolling in the help screen doesn't work with the arrow keys.
 - Within the sandbox sudo is not working for tools.
-- There is an exception if vigil's window is made too small.
 
 
 Current (tool related)
@@ -207,6 +206,9 @@ Fixed
   <- 'Watching' is never off now
 - When the filesystem changes a lot vigil is syncing the summary repeatedly
   for each part in a queue of changes. Needs to empty the queue then sync.
+- There is an exception if vigil's window is made too small.
+  <- When the window is narrower than 10 or shorter than 20 the contents
+     start to crop instead of shrink.
 
 
 On hold, run-tool related

vigil

@@ -761,7 +761,7 @@ class Screen:
         return [bar[:progress_bar_size].underline() + bar[progress_bar_size:]]
 
     def appearance(self, dimensions):
-        width, height = dimensions
+        width, height = max(dimensions[0], 10), max(dimensions[1], 20)
         if self._is_help_visible:
             return self._help_widget.appearance(dimensions)
         widget = self._summary.get_selection()
@@ -778,9 +778,12 @@ class Screen:
         status_bar_appearance = self._get_status_bar_appearance(
             width, self._summary.is_directory_sort, self._is_paused,
             progress_bar_size)
-        return (self._layouts[self._is_log_visible][self._is_listing_portrait]
-                .appearance((width, height-len(status_bar_appearance))) +
+        result = (self._layouts[self._is_log_visible]
+                  [self._is_listing_portrait] .appearance(
+                      (width, height-len(status_bar_appearance))) +
                   status_bar_appearance)
+        return (result if (width, height) == dimensions
+                else fill3.appearance_resize(result, dimensions))
 
     _KEY_DATA = [
         ({"t"}, toggle_window_orientation), ({"l"}, toggle_log),