GUI tool for level editor for mac

Tool must read in and write out a text file -- the level file. The level is a series of branches and items on/near the branch. Each of these is described by a single line of text, broken into five comma separated fields. Each of these fields are simple one word strings, except for the third, which is an integer. The level editor tool will need to run on a mac. The tools GUI will need to have a scrollable window that the user can adjust the size of, both vertical and horizontal( this won't affect the output of the level file ). On the side of this window will be a slim, scrollable window containing the elements the user can drag into the level editor window. The first time an item has been dragged into place in the level editor window, the item's properties will be set to default values. The default values will be different for each type of item. Right clicking on any item in the level will allow the user to edit the properties of that item in the level. Once an item has been added to the level, moving it somewhere else in the level should be permissible and easily done. Adding items usable in the level editor should be easily done. A text file for the tool will define the items usable in the tools GUI that the user can drag into the levels. It will consist of lines of text, each line will contain the name of the item, and the filename for the graphic. Special considerations - the levels are set up so that the branches are vertically evenly spaced . This spacing may change in the future. The level editor tool should allow for this spacing to change easily. There are many different types of branches. Branches are anchored on one side of the screen or the other, as described by the first property for that branch item -- either "LEFT" or "RIGHT" Once a branch has been added, any other non-branch item added is considered to be sitting on the branch. Once another branch is added, any other non-branch item added after that is now considered to be sitting on this new branch. A typical use case is as follows - User creates empty level. User drags "ground type forest" into level editor window. User drags "branch type A" into level editor window, placing it on the left side of the screen. User drags "snake" onto branch. User drags "branch type K" into level editor window, placing it on the right side of the screen. User drags "gold" onto branch. User drags "branch type A" into level editor window, placing it on the right side of the screen. User MOVES "gold" on previous branch onto new branch. Sample graphics files and level files will be provided to start.