Lock screen does not cover software buttons

[AlstonLin]

This means there would be inconsistent UI.
Cannot be fixed by elevating drawing priority-

(Tested with Nexus 5 on Genymotion)

[AlstonLin]

Solution:

We will need to attach a second view, consisting only of the background, to the window manager that has the following properties

• WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS flag enabled
• TYPE_SYSTEM_OVERLAY priority
• Cannot receive any touch input (so background only)
• Will also need to extend the width and height of the view to entire screen using

Point displaySize = new Point();
windowManager.getDefaultDisplay().getRealSize(displaySize);
...
params.height = displaySize.y;
params.width = displaySize.x;