dabbrev-check-other-buffersdabbrev-check-other-buffers is a variable defined in `
dabbrev.el'. Its value is
tDocumentation: Should M-/ look in other buffers? nil: Don't look in other buffers. t: Also look for expansions in the buffers pointed out by `dabbrev-select-buffers-function'. Anything else: When we can't find any more expansions in the current buffer, then ask the user whether to look in other buffers too. The default value is t. You can customize this variable.