The 'aplkeyboard' property

Integer scalar

Valid for: System object

The aplkeyboard property is an integer scalar which determines whether the APL keyboard mapping is in effect. Setting this property to 1 causes input to all APLX windows (including those created using ⎕NEW or ⎕WI) to use the user's preferred APL keyboard layout (unified or standard). Setting the value to 2 selects the 'standard' APL keyboard layout, and 3 selects the 'unified' APL keyboard layout. Setting it to 0 causes the ordinary non-APL layout to be used. This is particularly useful for packaged applications, where you typically want to switch off the APL keyboard layout.

When you read the value back, you always get either 0 (for non-APL layout) or 1 (for APL layout).