Arabic poem typeset for playing around with ConTeXt font handling

sailofyourtwoeyes.tex

%---------------------------------------------------------------------------
% Lovely without vowelisation: diwanibent (decorated), diwaniletter (fancy), 
%   scheherazade (conservative), oldanticdecorative, irannastaliq, bfantezy, 
%   bdavat, barabicstyle (like omani handwriting), arial (plain; readable),
%   andalus (kufi script), amiri (conservative; nice ligatures), tholoth
%
% Working well with vowelisation: rabat, arabictypesetting
%
% Not displaying correctly (i.e. broken): traditionalarabic
%
% Not displaying at all: timur, oibeyrutnormala, kacstonebold, helvan
%---------------------------------------------------------------------------

% Necessary to make Arabic text work properly
\definefontfamily[mainface][rm][arabictypesetting][features=arabic]
\definefontfamily[mainface][ss][diwanibent][features=arabic]
\definefontfamily[mainface][tt][amiri][features=arabic]
\setupbodyfont[mainface,rm]
\setupdirections[bidi=global]
\setupalign[r2l]

% Preparing the page for properly displaying vertically aligned content;
% setting up vertical spaces between paragraphs
\setuplayout[header=-6mm,footer=0mm,backspace=0mm,width=210mm]
\setuplines[before={\blank[14mm]},after={\blank[1em]}]

\starttext

% No page numbering; vertical alignment
\setupheader [state=stop]
\dontleavehmode
\vfill

\startalignment[middle]

\ss % Correct to use it this way?
\switchtobodyfont[150pt]
شراع
\crlf
\switchtobodyfont[126pt]
عينيك
\rm % Correct to use it this way?
\switchtobodyfont[20pt]
\startlines
عيناكِ في ألقِ الشَّعاع
كـنجمتَيـنِ في التَّماع
وشعـرُكِ الغافي على الْمَتَـنَين
لِمَلْمِهِ شراع

فإذا غفَا فيكِ الغرام
واستيقظَتْ في القلبِ آلامُ الهِـيام
أنا ذلكَ النِّضُو الشَّريد
أنا ذلكَ الهاوي البعيد

مَعْبُودَتِي - ما هكـذا جُعْلُ الغرام
إنِّي دُمُوعٌ موْغَلٌ فيها البُكـاء
إنِّي جُـذُورٌ يَستبيحُ دماءَ ها قحْطُ الشِّتاء
هل تسمِعيـن؟
وفي الْمَناحةِ ترْقَصِيـن؟
\stoplines
\tt % Correct to use it this way?
\switchtobodyfont[10pt]
(قصيدة من نظم هيثم الناهي)
\stopalignment % Ending horizontal alignment
\vfill         % Ending vertical alignment

\stoptext

(Works well with ConTeXt beta as of January 7th, 2015)