Bug report

Inconsistent navigation toolbar behavior between major versions

Bug summary
Recently moved from (A) Matplotlib 1.5.0 to (B) Matplotlib 2.1.2

The same code produce:
Case A: a larger window with the toolbar displayed
Case B: a smaller window with the toolbar hidden

Code for reproduction
Use any code from the example pages

Expected outcome
The toolbar behavior should be identical, or at least the change should be documented.
Personally I liked the behavior (A) better, as it saves the user a mouse click-and-drag movement (= welcome to CTS/RSI, folks) on every plot.
Alternatively, a way to control the bar appearance should be provided.

Matplotlib version

• Operating system: Windows 10.0.16299 AMD64
• Matplotlib version: (A) 1.5.0 and (B) 2.1.2 (pip install)
• Matplotlib backend: TkAgg
• Python version: (A) 3.4.3 and (B) 3.6.4
• Other libraries: numpy 1.13.3, scipy 1.0.0, PyQt4 4.11.4