Designing Games with Game Maker - YoYo Games

At the left top there is the current set of tiles used. To select the set, click on the menu button
below it and select the appropriate background image.
Now you can add tiles by selecting the tile you want at the top left, and next clicking at the
appropriate place in the room at the right. This works in exactly the same way as for adding
instances. Underlying tiles are removed, unless you uncheck the box Delete underlying. You
can use the right button to delete tiles. Hold the key to add multiple tiles. And hold
the key to move tiles to a new place. The key will avoid snapping to the gird.
Also there is again a pop- up menu when you hold the key and click on a tile with the
right mouse button. The buttons in the toolbar will now clear all tiles, shift all tiles, sort the
tiles or lock/unlock them. (Actually they only operate on the current layer; see below.)
In some situations you might want to put a part of the background in the room that is not
exactly the size of a tile or consists of multiple tiles. This can be done as follows. In the top-
left image press the left mouse button while holding the key. Now you can drag an area
which you can then place in the room in the same way as tiles. To select multiple tiles, hold
the key. Note that this only works correctly when there is no separation between the
tiles. If you want to select an area that is multiple of the room grid size, hold the key
rather than the key. (Note that you can actually change the key you hold during the
dragging. This can sometimes be useful.)