UPDATE:
SVG ZOOM IS POSSIBLE IN XNVIEW MP , AND NO CRASH!
however,
in the current beta release 
, the user
must right click to access Zoom in / Zoom out, the built-in Adobe SVG viewer** which appear on-right*-click [*alt-mouse], not unlike the Adobe (former, Macromedia) Flash viewer controls replace the 'default' context-menu, when the mouse hovers a 'Flash object' from the browser viewport
**as tested on windows Xp sp3. considering this seems to be associated w/ the XnView MP integration w/ Internet Explorer v8, again, as tested on Win XP, I apologize for I must warn that this info could not be accurate for Linux, as there is no OEM iE for linux [known to this user], and i can't speak for OS X. I suspect that XnView MP has accommodations [currently, or at least under development] for each platform. For example, on Linux, perhaps Konqueror, Galeon, or Epiphany is loaded [where iE is, in XP] in which case the WebKit or Gecko native capabilities would probably take over , (as it does by default, InternetExplorer in win while my default browser might be Safari [Webkit on Windows XP], or Gecko some such... Fire / 'monkey / 'zilla-mino-- it's always IE, in XnView MP). I believe it is also worthy to remark upon Internet Explorer being [methinks] the lone-ranger w/out SVG support, right? And, although Presto/ Opera supports SVG, as previously mentioned/rambleababled, albeit, it is not a default htmlviewer for any platform known to this luser, so is likely not-- ah who knows! Whatever the situation, on whatever platform-- i am confident that XnView development has this under control-- considering the whole point of MP is to be portable, cross-platform!... uh... right?
my apologies again, for less-than brilliant feedback. i'm sure the leaders will have a more informative direction on this topic, once they have time to address it properly. thanks again. for those who have yet to check it out-- you may find most success by using "Open With" from XnView 1.9x, pointing to XnView MP-- to open an SVG image (as i've found it the only way to successfully get MP to "view" SVG at all, but once you get there-- you're good to go! do a slideshow, right click, zoom out, do whatever. enjoy!)