New answers tagged text-input
Making the user input a tone used to be the default in OS X, but not since at least OS X 10.8. Now it continues to guess your characters as you keep typing, and since it's pretty good at guessing, I guess tone selection was deemed an unnecessary step. There may be some way you can fiddle with com.apple.inputmethod.SCIM.plist or com.apple.inputmethod.TCIM....
I think QIM may do this, but I have not verified it myself: http://www.laoshilink.org/laoshilink/QIM.html
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