Missing Channel Info Menu (in v0.5.7 on FFOS only)

[slonerde]

This is about telegram/webogram v0.5.7 on Firefox OS (FFOS 2.0) only:

v0.5.4 worked fine on FFOS for a long time without issues, until it recently failed to display channels' contents.
v0.5.7 brought back the missed channel contents, but breaks a function that worked before: the channels' info menu is missing.

ISSUE:
With v0.5.7 the channel information menu (titled "Channel Info" in v0.5.4) by clicking its icon does not show up any more.
This makes it impossible to leave a channel (by using the "Leave" item of the "three-vertical-dots" child menu like in v0.5.4).

Private chats (1:1) and bot messages (1:many) are not affected, here the corresponding menus (titled "Contact Info") do show up and work fine.

Because v0.5.7 seems to be the last working telegram app version for FFOS (neither v0.7.0, the current master version, nor the current two web versions do work on FFOS 2.0), it would be fine to have a patch for this version fixing the described issue.