<s>
In	O
event-driven	B-Application
computer	B-Application
programs	I-Application
,	O
an	O
event	B-General_Concept
cascade	I-General_Concept
occurs	O
when	O
an	O
event	O
handler	O
causes	O
another	O
event	O
to	O
occur	O
which	O
also	O
triggers	O
an	O
event	O
handler	O
.	O
</s>
<s>
This	O
can	O
be	O
a	O
tricky	O
source	O
of	O
program	O
errors	O
(	O
see	O
computer	B-Error_Name
bug	I-Error_Name
)	O
.	O
</s>
