NVIZ help not showing

[pcav]

In NVIZ, pressing Help returns: can't read "env(GRASS_HTML_BROWSER)": no such variable can't read "env(GRASS_HTML_BROWSER)": no such variable

while executing

"exec -- $env(GRASS_HTML_BROWSER) ​file://$env(GISBASE)/docs/html/nviz/$URL &"

(procedure "nviz_browse" line 4) invoked from within

"nviz_browse nviz_toc.html "NVIZ Help""

invoked from within

".top.menu.help.m invoke active"

("uplevel" body line 1) invoked from within

"uplevel #0 [list $w invoke active]"

(procedure "tk::MenuInvoke" line 50) invoked from within

"tk::MenuInvoke .top.menu.help.m 1"

(command bound to event)

[rblazek]

Fixed in r12915.