Displaying variables that were defined in a message box causes modal popup to disappear early

[kyle-kingsbury]

When you assign a value to a variable and then immediately try to display that variable value in a messagebox, the box will be exited automatically after about 3 seconds. If you wait 3 seconds and then display the message, it will not be exited automatically -- but will persist.
For example:
PX,-200,5,2
PAUSE, 0.1
&XPOS = %(1)
PAUSE, 0.1
PAUSE, "THIS IS YOUR XPOS " + &XPOS

The message will disappear

PX,-200,5,2
PAUSE, 0.1
&XPOS = %(1)
PAUSE, 0.1
PAUSE, "THIS IS YOUR XPOS " + &XPOS
PAUSE, "THIS IS YOUR XPOS " + &XPOS

The second message will stay displayed

PX,-200,5,2
PAUSE, 0.1
&XPOS = %(1)
PAUSE, 3
PAUSE, "THIS IS YOUR XPOS " + &XPOS

The message will stay.

It is not caused just by the variable being present in the message box. Any message box will be closed 3 seconds after assigning a variable value (after a probe move?)