Fix(VIM-2760) notebookCommandMode detection

[Runinho]

Hi,
I tried to fix VIM-2760 because it really annoyed me :D

notebookCommandMode always returns false which results in handling the enter key wrong when in command mode of the notebook.
I tried to fix that by checking the client property ActionUtil.ALLOW_PlAIN_LETTER_SHORTCUTS that is set by NotebookEditorModeListenerAdapter.

I don't know if this is just a hack or a viable way to do it.
Another option to fix the issue would be to create our own listener. Sadly, I can't manage to register one:

import org.jetbrains.plugins.notebooks.ui.editor.actions.command.mode.NOTEBOOK_EDITOR_MODE

NOTEBOOK_EDITOR_MODE.subscribe(null, MyNotebookEditorModeListenerAdapter())

results in the following error:

 Class org.jetbrains.plugins.notebooks.ui.editor.actions.command.mode.NotebookEditorModeKt must not be requested from main classloader of com.intellij plugin

If the client property method is ok, I think we can remove the HandlerInjector Class and move the static notebookCommandMode function somewhere else (maybe into helper/EditorHelper.kt).

Let me know if I should do that refactoring or if there is a better way to detect the command mode.

Thanks,
Runinho

[AlexPl292]

Hi there! Thank you for your fix. This is not a perfect solution, but an acceptable workaround.