Following a recent zypper update, SeaMonkey no longer correctly displays WebGL
graphics.

Other WebGL-enabled browsers, such as Firefox and Chromium, are not affected.

The problem is specific to the Tumbleweed package of SeaMonkey (currently
seamonkey-2.46-3.3.x86_64).  The problem is not reproducible with the official
and "contributed" builds of SeaMonkey 2.46 from
<https://www.seamonkey-project.org/releases/>.  The problem is also not
reproducible on my other systems running Leap 42.2 using the Leap 42.2
SeaMonkey packages.

The problem occurs even when running a completely new profile (i.e., all
settings at their defaults and no add-ons).

The problem manifests itself in missing lines on canvases, or even entirely
blank canvases.  For example:

1. On Weather Underground, the red temperature line on the forecast graph is
not rendered.  Example:
<https://www.wunderground.com/q/zmw:00000.60.WEDFE?sp=IDARMSTA75>  See attached
file "wunderground.png" for a side-by-side comparison of how the page is
rendered correctly in Firefox (top) and incorrectly in SeaMonkey (bottom).

2. On Google Maps, route lines are not shown when asking for directions. 
Example:
<https://www.google.co.uk/maps/dir/Vancouver,+BC,+Canada/Jasper,+Alberta,+Canada/@51.5994076,-121.0412464,7z/data=!4m14!4m13!1m5!1m1!1s0x548673f143a94fb3:0xbb9196ea9b81f38b!2m2!1d-123.1207375!2d49.2827291!1m5!1m1!1s0x53832b0868553e29:0x1f2002bd0b192882!2m2!1d-118.0813581!2d52.8736786!5i1>
 See attached file "googlemaps.png" for a side-by-side comparison of Firefox
(left) and SeaMonkey (right).

3. On <http://webglreport.com/>, the entire canvas is blank.  See "webgl.png"
for a side-by-side comparison of Firefox (left) and SeaMonkey (right).