error on go get

[leonardo]

$ go get -u github.com/google/gxui/...
# github.com/google/gxui/drivers/gl
../../go/src/github.com/google/gxui/drivers/gl/driver.go:191:12: assignment mismatch: 2 variables but c.window.Window.GetClipboardString returns 1 values

[Kvaz1r]

See #178