In Glines 1.0.51, if you click on a ball while another ball is moving,
you trigger a bug which has a few different symptoms.

First off, the moving ball stops without reaching its destination, but
is effectively no longer there -- another ball that moves later may
go through that space and annihilate it.

The new ball you clicked on may go to its destination when you click
somewhere, and all will be well, but usually it jumps to the upper-left-hand
corner, annihiliating any ball already there.

Once a ball jumps there, further attempts to play will cause balls you
try to move to instead jump to that corner, until you run out of other
balls (typical if you trigger this early in a game) or until something
causes it to fix itself.  In my experience, what causes it to fix itself
has seemed erratic, but short straight moves and illegal moves tend to
do this.