[rfc][icedtea-web] SecurityDialog centers itself after becoming visible

[Jacob Wisor]

Andrew Azores wrote:
> Hi,
> 
> It kind of bothered me that our SecurityDialog windows would appear 
> briefly in the top left corner of the screen before becoming centered. 
> Maybe it's less apparent with other window managers that have fancier 
> effects and animations, but it's incredibly obvious with OpenBox at least.
> 
> This was happening because the centerDialog() call was being made after 
> a windowOpened event was fired, which happens after the window becomes 
> visible. Moving the centerDialog call out of that handler and into the 
> initialization of the dialog itself, some time after pack() is called, 
> fixes this. This way the window position is already set to the middle of 
> the screen well before the window becomes visible, and the Dialog is 
> much less jarring when it does appear IMO.

Looks good to me and greatly appreciated! :)
Would you mind back porting it to 1.4 too?

Regards,
Jacob