   Creating Tile Maps
  Creating the map editor for my clunky tile engine and have run into a design issue.  For the people that have already done this, do you have several predefined map sizes or do you let the user create the map sized as they need it?  Right now I'm trying to lean towards having the user create the size by inserting rows/columns.  That presents a problem of where to insert and how the move tiles if the insert is in the middle of the map.  Another option I guess is when the user creates the new map I have a dialog for them to input height and width.   
  I would say go for the option of asking the user what size map they want using a dialog box of some sorts before they start making a map.  Then additionally if you wanted to, you could have an option to increase the size by simply tacking on n amount or rows and columns.  I see this setup used a lot in RTS games myself, however I suppose it depends a lot on what you need done.For my own part, my tile engines in the past have always asked what the map size is and once it's set it can't be changed without redoing the entire map.  This worked fine for my RTS and action/adventure games, but perhaps if I were creating a puzzle game of sorts, I would supply the user with some more powerful tools.   ;  I'm trying to make like a Mario side scroller.All the map editors I have seen have been for RTS and they just had you select the size before you started and thats all there was.  I think it wouldn't be to hard to enter the size on start then have the ability to resize the whole map via a similar dialog box.   