Demonstrates how to open several windows after each other.

Expected order of execution:

• When the example runs a first window will be shown.
• Once the first window is closed after a delay a second window will be shown.
• Similarly, when the second window is closed after a delay a third will be shown.
• Once the third is closed the program will stop.

NOTE: this doesn't work on Mac. See also #1918.

cargo run -p serial_windows