widget: no newline in editor on submit

When you press enter to "submit" an editor widget, don't also append the
newline to the editor text.  Enter should be "submit" or "add newline"
but not both.

Also add parens to the Enter check: x && y || z => x && (y || z).

Signed-off-by: Larry Clapp <larry@theclapp.org>

widget/editor.go

@@ -153,11 +153,12 @@ func (e *Editor) processKey(gtx *layout.Context) {
 			if !e.focused {
 				break
 			}
-			if e.Submit && ke.Name == key.NameReturn || ke.Name == key.NameEnter {
+			if e.Submit && (ke.Name == key.NameReturn || ke.Name == key.NameEnter) {
 				if !ke.Modifiers.Contain(key.ModShift) {
 					e.events = append(e.events, SubmitEvent{
 						Text: e.Text(),
 					})
+					return
 				}
 			}
 			if e.command(ke) {