like in most inform / tads interpreter, to be able to redo last command with up arrow on keyboard
You can do this already by pressing the F12 key.
default game open / save / load etc. is "My documents". Last folder used could be better for those who store games and save games elsewhere.
Go to Options, then Other, and then click the "Browse" button to choose the default folder.
But to be able to add images inside the text window (like in inform / glux, Hugo or Tads) could be very great and opens new possibilities.
This is one that's already on my list of things to add, and it might make the release version of Quest 3.5. You'll be able to split the Quest window up into two panes - one for text and the other for graphics.
Adding in-line graphics would be a bit harder and would require rewriting the text output code to use something other than the RichText control, which doesn't support in-line graphics. This is something I'm planning at some point but it will require a bit of work.
possibility to start a game with only the text window (no inventory, places and objects, and compass windows)
In the game startscript you can add "panes on" or "panes off" to toggle the view of panes. I don't seem to have remembered to add this to QDK though - woops! I'll add it into the release version of QDK 3.5. Until then you can add "panes off" by choosing "Other script command" and typing it in.
is it possible to easily create a text based menu only
No, but you could "fake" one, by using the "enter" command (in QDK, in the "Other" category, "Enter next command into a string variable") and getting the player to type in their choice.
possibility to use in the script of a game the ldf definition so the game will load with the correct langage support.
This will be added when the LDF format has been developed further. At the moment since it doesn't offer full support for translating in-game text, I haven't added this facility, but I will as develop the LDF translation interface.
hope new version of Quest won't require new translation of the ldf file, but will be add ons for the language.
New versions will of course need a few extra things to be translated, but they won't require a completely new LDF file to be created from scratch.
Thanks for your suggestions - keep them coming