README corrections. Visual tweak to CloseButton.

README.md

@@ -806,19 +806,19 @@ Optional keyword only arguments:
  * `textcolor=None` Text color. Defaults to `fgcolor`.
  * `litcolor=None` If provided the button will display this color for one
  second after being pressed.
- * `text` Shown in centre of button. Default: an empty string.
+ * `text=''` Shown in centre of button.
- * `callback` Callback function which runs when button is pressed.
+ * `callback=dolittle` Callback function which runs when button is pressed.
- * `args` A list/tuple of arguments for the above callback. Default `[]`.
+ * `args=()` A list/tuple of arguments for the above callback.
- * `onrelease` Default `False`. If `True` the callback will occur when the
+ * `onrelease=False` If `True` the callback will occur when the `select`
- `select` pushbutton is released otherwise it will occur when pressed.
+ pushbutton is released otherwise it will occur when pressed.
 
 Method:
- * `greyed_out` Optional Boolean argument `val` default `None`. If
+ * `greyed_out=None` Optional Boolean argument `val`. If `None` returns the
- `None` returns the current 'greyed out' status of the control. Otherwise
+ current 'greyed out' status of the control. Otherwise enables or disables it,
- enables or disables it, showing it in its new state.
+ showing it in its new state.
 
 Class variable:
- * `lit_time` Period in seconds the `litcolor` is displayed. Default 1.
+ * `lit_time=1` Period in seconds the `litcolor` is displayed.
 
 ### CloseButton
 
@@ -828,6 +828,16 @@ right hand corner of the current `Screen`. Operating it causes the screen to
 close, with the screen below being revealed. On the bottom level screen, a
 `CloseButton` will shut down the application.
 
+Constructor mandatory positional arg:  
+ * writer
+
+Optional keyword only arguments:  
+ * `width=0` By default dimensions are calculated from font size. The button is
+ is square. Optionally `width` may be specified.
+ * `callback=dolittle` Optional callback, not normally required.
+ * `args=()` Args for above.
+ * `bgcolor=RED`
+
 ###### [Contents](./README.md#0-contents)
 
 # 10. ButtonList object
@@ -850,18 +860,28 @@ However each button can have its own list of `args`. Callback arguments
 comprise the currently visible button followed by its arguments.
 
 Constructor argument:
- * `callback` The callback function. Default does nothing.
+ * `callback=dolittle` The callback function. Default does nothing.
 
 Methods:
  * `add_button` Adds a button to the `ButtonList`. Arguments: as per the
  `Button` constructor.
  Returns the button object.
- * `greyed_out` Optional Boolean argument `val` default `None`. If
+ * `greyed_out=None` Optional Boolean argument `val`. If `None` returns the
- `None` returns the current 'greyed out' status of the control. Otherwise
+ current 'greyed out' status of the control. Otherwise enables or disables it,
- enables or disables it, showing it in its new state.
+ showing it in its new state.
- * `value` Optional argument: a button in the set. If supplied and the button
+ * `value` Optional args `button=None`, `new_cb=False`. The `button` arg, if
- is not active the currency changes to the supplied button and its callback is
+ provided, should be a button in the set. If supplied and the button is not
- run. Always returns the active button.
+ active the currency changes to the supplied button, which is displayed. By
+ default the callback of the previous button is run, otherwise the callback of
+ the newly displayed button. 
+
+Always returns the active button.
+
+Counter intuitively, running the callback of the previous button is normal
+behaviour. Consider a `ButtonList` consisting of ON and OFF buttons. If ON is
+visible this implies that the machine under control is off. Pressing `select`
+causes the ON callback to run, starting the machine. The new button displayed
+now reads OFF.
 
 Typical usage is as follows:
 ```python
@@ -899,9 +919,9 @@ Constructor positional arguments:
 Methods:
  * `add_button` Adds a button. Arguments: as per the `Button` constructor.
  Returns the Button instance.
- * `greyed_out` Optional Boolean argument `val` default `None`. If
+ * `greyed_out=None` Optional Boolean argument `val`. If `None` returns the
- `None` returns the current 'greyed out' status of the control. Otherwise
+ current 'greyed out' status of the control. Otherwise enables or disables it,
- enables or disables it, showing it in its new state.
+ showing it in its new state.
  * `value` Optional argument: a button in the set. If supplied, and the
  button is not currently active, the currency changes to the supplied button
  and its callback is run. Always returns the currently active button.

gui/widgets/buttons.py

@@ -100,7 +100,9 @@ class Button(Widget):
 class CloseButton(Button):
     def __init__(self, writer, width=0, callback=dolittle, args=(), bgcolor=RED):
         scr = Screen.current_screen
-        wd = max(writer.stringlen('X') + 6, width)
+        # The factor of 2 is an empirical fix to make it look OK over
+        # the range of fonts in use.
+        wd = width if width else writer.stringlen('X') * 2
         self.user_cb = callback
         self.user_args = args
         super().__init__(writer, *scr.locn(4, scr.width - wd - 4),