Gets or sets a value indicating whether the left mouse button is currently down.
Object.defineProperty(AnnDesigner.prototype, 'isMouseLeftButtonDown',
get: function(),
set: function(value)
)
isMouseLeftButtonDown: boolean;
true if the left mouse button is currently down; otherwise, it is false.
For touch-enabled devices, the touch input is always treated as the left button. So IsMouseLeftButtonDown will be true if the user has a pressed a finger on the device and false otherwise.