Just a list of the hotkeys for modifying tiles in the tooslet, so they get not overlooked (which can happen easily).
First you need to select a tile (from tile list or - with upcoming next IB2 beta - from the main map itself). Then press one of the following keys before placing the tile to modifiy its microposition, size, rotation, mirror state or transparency:
w,a,s,d - move tile pixel wise (you can paint "between" squares this way)
q,e - enlarge or shrink a tile
r,t - rotate a tile by 90% clock wise or counter clockwise, with shift you make a more precise rotation by 1 degree steps (just keep the button held down); note: t will start to work with upcoming IB2 beta
f,g - change transparency/opacity of tile, making it "look through"; this is great for blending ground types on each other, will start to work with upcoming IB2 beta
m - mirror a tile by a vertical mirror axis right through its center
Note: with current IB2 beta - when using the allTilesSystem - this does not work in engine, fix is already inlcuded in next release (in March)