Question

"<Keyboard>" does not set the required layout_height attribute:
 (1) Set to "wrap_content"
 (2) Set to "fill_parent"
"<Row>" does not set the required layout_width attribute:
 (1) Set to "wrap_content"
 (2) Set to "fill_parent"
"<Row>" does not set the required layout_height attribute:
 (1) Set to "wrap_content"
 (2) Set to "fill_parent"
"<Key>" does not set the required layout_width attribute:
 (1) Set to "wrap_content"
 (2) Set to "fill_parent"
"<Key>" does not set the required layout_height attribute:
 (1) Set to "wrap_content"
 (2) Set to "fill_parent"
com.android.layoutlib.bridge.MockView cannot be cast to android.view.ViewGroup
You must supply a layout_height attribute.
Exception details are logged in Window > Show View > Error Log
The following classes could not be found:
- Keyboard (Fix Build Path, Edit XML)
- Row (Fix Build Path, Edit XML)
- com.example.android.softkeyboard.LatinKeyboardView (Fix Build Path, Edit XML, Create Class)

Answer 1

It means that your xml keyboard layout file is missing android:layout_width and/or android:layout_height for some of the components.

EDIT

On second glance, it looks like you are putting your keyboard layout file in the res/layout folder. It belongs in the res/xml folder.