REUTERS/Khaled AbdullahCAIRO (Reuters) - Egypt's public prosecutor on Tuesday ordered the detention of ex-presidential candidate Khalid Ali for questioning in relation to a case in which he is accused of "offending public decency," his lawyer told Reuters. Ali, a prominent human rights lawyer who ran in Egypt's 2012 election, has suggested he might run against President Abdel Fattah al-Sisi in a presidential election slated for 2018. Ali is being sued by a private citizen over a photograph in which he appears to make a rude hand gesture on the steps of a Cairo court house, according to his lawyer Malek Adly.