Re: Idioms containing names of cities
Old Delhi, the capitol in MuGhal period, was a very small area and the village Palam [where the International Airport lies (it’s old name was Palam Airport)] was a short distance [22 km] away hence they coined this phrase to emphasize Shah Alam’s range of reign.
in todays terms, it’s like Karzai whose rule extends to within the boundaries of Kabul only! 
it means: If you share your vital secret with someone untrustworthy, it will come to haunt you in a big way and you’ll regret sharing with him/her.
no…i never heard. 
aate haiN Ghai’b se yeh moHaavaraat Khayaal meN!!! 