This PR exposes the ability to control the duration of a StatusBar message (qt only for now). I am creating this PR to start the discussion:

• Would others agree that this is desirable?
• How to handle Wx since its wx.StatusBar doesn't expose the same ability? What's pyface's policy for exposing toolkit specific capabilities? If that's not acceptable, a similar behavior could be implemented using a wx.Timer: https://stackoverflow.com/questions/23188042/wxpython-statusbar-temporary-text . That feels like a lot of complexity brought into pyface though.

Codecov Report

Merging #522 into master will increase coverage by 0.95%. The diff coverage is 62.93%.

@@            Coverage Diff             @@
##           master     #522      +/-   ##
==========================================
+ Coverage   37.08%   38.04%   +0.95%     
==========================================
  Files         470      470              
  Lines       26027    26184     +157     
  Branches     3961     3975      +14     
==========================================
+ Hits         9652     9961     +309     
+ Misses      15948    15788     -160     
- Partials      427      435       +8     

Impacted Files	Coverage Δ
pyface/__init__.py	82.60% <ø> (ø)
pyface/ui/wx/action/status_bar_manager.py	31.91% <31.25%> (+2.36%)	:arrow_up:
pyface/ui/qt4/init.py	62.50% <33.33%> (ø)
pyface/ui/qt4/workbench/split_tab_widget.py	12.47% <50.00%> (ø)
pyface/qt/QtNetwork.py	75.00% <60.00%> (ø)
pyface/qt/QtOpenGL.py	75.00% <60.00%> (ø)
pyface/qt/QtSvg.py	75.00% <60.00%> (ø)
pyface/qt/QtTest.py	75.00% <60.00%> (ø)
pyface/qt/QtWebKit.py	68.42% <60.00%> (ø)
pyface/qt/QtCore.py	77.77% <62.50%> (ø)
... and 36 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update c98d1d3...6f0dc56. Read the comment docs.

This is ready for a second look. WX support added, implementation redone for Qt, unit test added.

Test failure only happens with pyqt, not pyqt5 and is triggered by the following exception in the listener:

Exception occurred in traits notification handler.
Please check the log file for details.
Exception occurred in traits notification handler for object: <pyface.ui.qt4.action.status_bar_manager.StatusBarManager object at 0x127802888>, trait: messages, old value: ['goodbye world'], new value: []
Traceback (most recent call last):
  File "/Users/jrocher/.edm/envs/bootstrap3/lib/python3.6/site-packages/traits/trait_notifiers.py", line 381, in __call__
    self.handler(*args)
  File "/Users/jrocher/Projects/ETS_source/pyface/pyface/ui/qt4/action/status_bar_manager.py", line 100, in _messages_changed
    self._show_messages()
  File "/Users/jrocher/Projects/ETS_source/pyface/pyface/ui/qt4/action/status_bar_manager.py", line 142, in _show_messages
    self.status_bar.showMessage("  ".join(self.messages))
RuntimeError: wrapped C/C++ object of type QStatusBar has been deleted

Can't make sense of it. Any suggestions?

If the UI is closed before the timer gets to run its action, then when the timer's action is run, it would be accessing deleted objects. I think in the remove_status_bar method, we should stop and remove the timer if there is one. See if that resolves the error you saw?

Thanks for the suggestion @kitchoi . Didn't help with the test failure, but good suggestion anyway, so added.