Arrow keys do not work when editing expressions

Further information:

HOW TO REPEAT

Start Watchmaker phone app on any QWERTY slider phone (or specifically on a Motorola Photon Q) *with the keyboard already open*.

Create any element and select any expression of that element, for example create an image element then press on the right-hand side of the X position field to edit the X position expression.

Enter some text then press the left arrow key follow by the right arrow key.

EXPECTED BEHAVIOUR

Cursor moves one character to the left then one character to the right.

ACTUAL BEHAVIOUR

Cursor does not move.