I was experimenting with an early, early version of the Java SDK, v1.0.1, about 30 years ago. I was trying to build a calendar using a GridBagLayout, and all the date squares got scrambled and drew on top of each other. I posted to mailing lists and USENET, asking what exactly I was doing wrong, since—recalling the first rule of compiler bugs, to wit, "it's probably not a compiler bug"—while I thought I was "holding it correctly" (i.e., using the APIs in the manner recommended by the documentation), I was willing to concede that I was missing something important.

Turns out it was a bug in the Java runtime, one that was fixed in v1.0.3.