If you prefer having the tools at the left window side, you can chose an alternative pane layout in the preferences dialog. Restart DLE to let the change take effect.
You can zoom in out by simultaneously pressing shift, the left mouse button and moving the mouse.
Generally, the cursor will change depending on the function performed with the mouse.
The numpad plus and minus key functions have changed. They do not increase/decrease the current mine element, but add/delete cubes. That is because there are keyboards that only have an insert key on the numeric keypad(e.g. mine , and that makes switching between inserting cubes and geometry editing via the numeric keypad very tedious.
Instead of 'A' and 'Z', numpad multiply and divide will zoom in and out of the mine.
Pressing the tab key will switch to the opposite side of the current side. This is a convenient short cut for the wall tool's 'other side' command.
As there is no low res mode anymore, the F6 key has been remapped to turn the variable light animation on and off.
You can toggle full screen mode with the F11 key.
Unlike DMB2, DLE will not delete 'unknown textures' from POG files when saving them.
The HOG file manager will display the list of the contained files alphabetically sorted. For better overview, you can make it display only level and related files (rdl/rl2, pog, hxm).
The HOG file manager will not erroneously delete files from the hog file that share the base name with a level file from the hog file, like DMB2 did.
DLE can save and read extended block files (extension: '.blx'). To save a block as extended block file, simply chose the extend block file type in the save file dialog.
Extended block files can contain special segment data (robot maker/fuel center/reactor), walls and triggers. Only those walls and triggers belonging to a marked segment will be saved in an extended block file, and only trigger targets lieing in the saved block will be saved (this can lead to triggers with empty target lists being stored in an extended block file - to locate them, run a level check after loading an extended block file).
DLE has an undo function allowing to revert from up to 100 editing steps, or redo undone changes.