quick and dirty test plan

TESTING.md

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+## Things to test
+
+1. basic operation: window opens and closes upon click, returning expected value
+2. double open: open, close, re-open in the same session
+3. timing: perform basic operational test many many times with reloads between
+4. explicit dialog close: closing dialog with key combo or X should return error to caller
+5. caller close while dialog open: closing the opener should close the window
+6. exceptional code: when possible, client code that throws an exception should cause error return