Hi John,
Thanks for your reply. Yes iv'e found why the CSS was removed when I clicked a link, it seems to have with crossplattform compatibility to do and lack of information.
The problem is in spmenu.js; onMBMD() and onMBMU() tries to apply a border and calls the method applyBorder(). In applyBorder() the CSS rule is changed for Mac compliance, "oCell.className = spm_fixCSSForMac(this.getIntCSSName('spmbar spmitmsel') + ' ' + this.cssMenuItemSel + ' ' + spm_getAttr(oCell, 'saveselcss', ''));"
When using the attribute "RootMenuItemActiveCssClass" it get's written to the DOM model as attribute "css". It's therefore not possible to save the classname in an instance variable in the SolpartMenu JS class(Like the default attributes do, ex. cssMenuItemSel).
The easiest solution to this is to comment out the above Mac compliance row that changes the "className" attribute. A better solution is probably to represent "RootMenuItemActiveCssClass" as something else than the "css" attribute in the DOM model and save that value to an instance variable(Like the defaults). It's then possible to remove all the places that these things can happen and still be crossplatform.
I will check the mentioned menus aswell, the SolpartMenu is rather limited and I'm looking for other free alternatives. If anyone know of more great free menus, please post in this thread.