GMail uses a large number of java scripts to make pages work. This javascript manipulates the HTML DOM.
If you look at the source of the page, you will not see the current contents of the DOM. You need to use a tool that will show you the HTML DOM. I use Opera Dragonfly, but there are many others for other browsers. Dragonfly will show the scripts for the page, as well as event handlers for each DOM element.
Edited Nov 3, 08:
In response to a request for access to scripts, when I look at the page, all scripts come out as embedded scripts. As others have said, they are confusing, so they are easier to read. Here is just a sample:
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function pa(a,b){return a.load=b}function d(a,b){return a.innerHTML=b}function qa(a,b){return a.onerror=b}function sa(a,b){return a.getDate=b}function ta(a,b){return a.value=b}function ua(a,b){return a.disabled=b}function va(a,b){return a.dispatchEvent=b}function wa(a,b){return a.currentTarget=b}function xa(a,b){return a.left=b}function ya(a,b){return a.hideFocus=b}function za(a,b){return a.removeChild=b}function Aa(a,b){return a.target=b}function Ba(a,b){return a.screenX=b}
function Ca(a,b){return a.screenY=b}function Da(a,b){return a.send=b}function Ea(a,b){return a.remove=b}function Fa(a,b){return a.start=b}function Ga(a,b){return a.cssText=b}function Ha(a,b){return a.keyCode=b}function Ia(a,b){return a.enabled=b}function Ja(a,b){return a.href=b}function Ka(a,b){return a.handleEvent=b}function La(a,b){return a.removeNode=b}function Ma(a,b){return a.detach=b}function Na(a,b){return a.type=b}function Oa(a,b){return a.contains=b}function Pa(a,b){return a.tabIndex=b}
function Qa(a,b){return a.cellSpacing=b}function Ra(a,b){return a.clear=b}function Sa(a,b){return a.setPosition=b}function Ta(a,b){return a.cellPadding=b}function Ua(a,b){return a.display=b}function Va(a,b){return a.execute=b}function Wa(a,b){return a.height=b}function Xa(a,b){return a.nodeValue=b}function Ya(a,b){return a.clientX=b}function Za(a,b){return a.clientY=b}function ab(a,b){return a.right=b}function bb(a,b){return a.visibility=b}
function aaa(a){var b=cb[i](db);(new Image).src=baa+eb(b)+"&jsmsg="+eb(a)+caa+fb+daa+(new Date)[gb]()}function _B_record(){cb[k]((new Date)[gb]())}function _B_prog(a){top.pr=a;if(hb===undefined){var b=top[ib][jb](eaa);hb=b?b[m]:null}if(hb){ka(hb,n[kb](a*0.99)+lb);if(a==100)hb=null}}function _B_err(a){aaa(a);throw a;}function mb(a,b){var c=a[nb](ob),e=b||pb;for(var f;f=c[rb]();)if(e[f])e=e[f];else return null;return e}function sb(){}function tb(a){a.lg=function $(){return a.bmc||(a.bmc=new a)}}
function ub(a){var b=typeof a;if(b==vb)if(a){if(typeof a[o]==wb&&typeof a[xb]!="undefined"&&!faa(a,gaa))return yb;if(typeof a[q]!="undefined")return zb}else return Ab;else if(b==zb&&typeof a[q]=="undefined")return vb;return b}function haa(a,b){if(b in a)for(var c in a)if(c==b&&Bb[r][Cb][q](a,b))return true;return false}function Db(a){return typeof a!="undefined"}function Eb(a){return ub(a)==yb}function Fb(a){var b=ub(a);return b==yb||b==vb&&typeof a[o]==wb}function Gb(a){return typeof a==Hb}
function Ib(a){return typeof a==wb}function Jb(a){return ub(a)==zb}function Kb(a){var b=ub(a);return b==vb||b==yb||b==zb}function Lb(a){if(a[Cb]&&a[Cb](iaa)){var b=a.closure_hashCode_;if(b)return b}a.closure_hashCode_||(a.closure_hashCode_=++jaa);return a.closure_hashCode_}
function s(a,b){var c=a.SSb;if(arguments[o]>2){var e=Array[r][Mb][q](arguments,2);c&&e[Nb][Ob](e,c);c=e}b=a.WSb||b;a=a.TSb||a;var f,g=b||pb;f=c?function(){var h=Array[r][Mb][q](arguments);h[Nb][Ob](h,c);return a[Ob](g,h)}:function(){return a[Ob](g,arguments)};f.SSb=c;f.WSb=b;f.TSb=a;return f}function Pb(a){var b=Array[r][Mb][q](arguments,1);b[Nb](a,null);return s[Ob](null,b)}function Qb(a,b){for(var c in b)a[c]=b[c]}
function t(a,b){function c(){}c.prototype=b[r];a.F=b[r];a.prototype=new c;a[r].constructor=a}function Rb(a,b,c){if(a[Sb])return a[Sb](b,c);if(Array[Sb])return Array[Sb](a,b,c);var e=c==null?0:c<0?n.max(0,a[o]+c):c;for(var f=e;f<a[o];f++)if(f in a&&a[f]===b)return f;return-1}function Tb(a,b,c){if(a[Ub])a[Ub](b,c);else if(Array[Ub])Array[Ub](a,b,c);else{var e=a[o],f=Gb(a)?a[nb](v):a;for(var g=0;g<e;g++)g in f&&b[q](c,f[g],g,a)}}
function Vb(a,b,c){if(a.map)return a.map(b,c);if(Array.map)return Array.map(a,b,c);var e=a[o],f=[],g=0,h=Gb(a)?a[nb](v):a;for(var j=0;j<e;j++)if(j in h)f[g++]=b[q](c,h[j],j,a);return f}function Wb(a,b,c){if(a[Xb])return a[Xb](b,c);if(Array[Xb])return Array[Xb](a,b,c);var e=a[o],f=Gb(a)?a[nb](v):a;for(var g=0;g<e;g++)if(g in f&&b[q](c,f[g],g,a))return true;return false}