MacOS – Is it possible to type in macron (e.g. “ā”) without using U.S. Extended Keyboard

Using the tab key between save and cancel buttons works for OS X too. You only have to enable it:

1. Go to System Preferences
2. Go To Keyboard
3. Go to the tab Keyboard Short
4. On the bottom of the window, set the radio button to "All controls":

From now on, when you see a OK/Cancel window the OK button is blue and can be pressed using the return key, and the cancel button has a outline which can be pressed using the space bar:

But the real trick is: You are now able to press the tab key to move the outline to another button and hit the space bar to press the highlighted button.

I ran into the same issue with Chinese and Japanese. (The icon on the menu bar changed but the input source was not actually changed until I switched to another input source and back.) It's a known bug according to a post at Karabiner's mailing list:

It's one of the most annoying bug of OS X.

Changing CJK input sources directly from program is not handled appropriately.

So, you need the following procedures.

Step1:
Enable "Select next source in Input menu" (command-option-space) on System Preferences > Keyboard > Shortcuts.

Step2:
Change input source by sending command-option-space.

<autogen>
  __KeyToKey__
  KeyCode::K, ModifierFlag::OPTION_L,
  KeyCode::VK_CHANGE_INPUTMODE_US,
  KeyCode::VK_WAIT_100MS,
  KeyCode::SPACE, ModifierFlag::COMMAND_R | ModifierFlag::OPTION_L,
  <!-- adjust wait for your machine -->
  KeyCode::VK_WAIT_10MS,
  KeyCode::VK_WAIT_10MS,
  KeyCode::VK_WAIT_10MS,
  KeyCode::SPACE, ModifierFlag::COMMAND_R | ModifierFlag::OPTION_L,
  <!-- adjust wait for your machine -->
  KeyCode::VK_WAIT_10MS,
  KeyCode::VK_WAIT_10MS,
  KeyCode::VK_WAIT_10MS,
  KeyCode::SPACE, ModifierFlag::COMMAND_R | ModifierFlag::OPTION_L,

  Option::NOREPEAT,
</autogen>

changeinput is affected by the same bug.

Another workaround is to just change to another input source and back:

<root>
  <vkchangeinputsourcedef>
    <name>KeyCode::VK_CHANGE_INPUTSOURCE_HIRAGANA</name>
    <inputsourceid_equal>com.apple.inputmethod.Kotoeri.Japanese</inputsourceid_equal>
  </vkchangeinputsourcedef>
  <vkchangeinputsourcedef>
    <name>KeyCode::VK_CHANGE_INPUTSOURCE_SPANISH</name>
    <inputsourceid_equal>com.apple.keylayout.Spanish</inputsourceid_equal>
  </vkchangeinputsourcedef>
  <vkchangeinputsourcedef>
    <name>KeyCode::VK_CHANGE_INPUTSOURCE_US</name>
    <inputsourceid_equal>com.apple.keylayout.US</inputsourceid_equal>
  </vkchangeinputsourcedef>
  <vkchangeinputsourcedef>
    <name>KeyCode::VK_CHANGE_INPUTSOURCE_CHINESE</name>
    <inputsourceid_equal>com.apple.inputmethod.TCIM.Pinyin</inputsourceid_equal>
  </vkchangeinputsourcedef>
  <item>
    <name>inputsources</name>
    <identifier>inputsources</identifier>
    <autogen>__KeyOverlaidModifier__ KeyCode::COMMAND_L, ModifierFlag::COMMAND_L | ModifierFlag::NONE, KeyCode::VK_CHANGE_INPUTSOURCE_US, KeyCode::COMMAND_L</autogen>
    <autogen>__KeyOverlaidModifier__ KeyCode::COMMAND_R, ModifierFlag::COMMAND_R | ModifierFlag::NONE, KeyCode::VK_CHANGE_INPUTSOURCE_SPANISH, KeyCode::COMMAND_R</autogen>
    <autogen>__KeyToKey__ KeyCode::C, ModifierFlag::OPTION_L | ModifierFlag::COMMAND_L | ModifierFlag::NONE, KeyCode::VK_CHANGE_INPUTSOURCE_CHINESE, KeyCode::VK_CHANGE_INPUTSOURCE_US, KeyCode::VK_CHANGE_INPUTSOURCE_CHINESE</autogen>
    <autogen>__KeyToKey__ KeyCode::C, ModifierFlag::OPTION_R | ModifierFlag::COMMAND_R | ModifierFlag::NONE, KeyCode::VK_CHANGE_INPUTSOURCE_HIRAGANA, KeyCode::VK_CHANGE_INPUTSOURCE_US, KeyCode::VK_CHANGE_INPUTSOURCE_HIRAGANA</autogen>
  </item>
</root>