Though the above summary tells you all you need to know about the problem let me try to explain it as best I can from a user perspective so that you understand why it's so important. Note that I am a power user that is heavily into keyboard shortcuts, doing things with the keyboard in general so long as it's not drastically slower than doing it with the mouse, and one who likes to get things done as efficiently and flexibly as possible(yes I'm aware there is often a tradeoff between the two but there is just as often a great compromise as well) so this may be a bit biased accordingly.

GNOME 3 while it has many problems gets one thing very very right that I haven't found adequately built into any other Open Source desktop. Some others like KDE, Unity, and Cinnamon do try but they haven't quite gotten it down as well as GNOME 3.

Assume I quickly want to launch a random program which I may not necessarily know ahead of time. Therefore even if I do something like bind the keyboard shortcut Super+E to Kwrite if I instead want to quickly launch firefox things like that won't do me any good unless I also rigged a similar binding like Super+W for firefox ahead of time. Keybindings like this are the fastest way to launch a program but they must all be statically determined ahead of time.

This was a problem which GNOME 3 solves very elegently with very little overhead. Say I want to launch a random program. To do so I press the Super button and then start typing it's name. As soon as I type the first letter it snaps out of the expose style overview of the windows and shows me the possible results. The first of these results is always clearly highlighted and I can launch it at any time by pressing enter without having to type any further to refine my search down to one possibility if it's already pointing to the program I want. This is a key point.

Of course without one more detail the previous point would be moot. What makes GNOME 3 so coldbloodedly efficient is that unlike some other desktops most notably Cinnamon it learns what programs I use most often and adjusts the search results accordingly. At first to launch Firefox I might have had to use a fairly long sequence of keys like Super f i r e Enter. After a short while it learns and now all I have to do is Super f Enter. Boom. Fast as a fiddle. Slower than Super+W but only slightly and considering the dynamic flexibility of such a system that little bit of overhead pays for itself a hundred times over.

In the other corner we have KDE. Note that in the summary above I didn't state whether the problem was specific to the main Kickoff menu, or the Lancelot Menu, or Krunner which is usually bound to Alt+F2(in my case Super+x but that shouldn't matter at all). This is mainly because barring maybe one or two minor details it is essentially identical for all three of them whichever of the launching services I use.

After invoking whatever launching service say Krunner for argument's sake I start typing. I type the first character of the program. Nothing. I type the second character of the program. Nothing. I type the third Finally I start seeing results. Like this is definitely not as bad as all that excrutiatingly slow pointing and clicking through menus. It's also certainly more flexible than a finite static set of keybindings to launch programs. However it is much slower than it could be and is clearly not the optimum solution to the whole search and quickly launch things problem.

Like in Krunner after the first query once I type the first letter of something I queried before it shows up in black and after the cursor several more appear in gray almost as a hint. But no results are visible yet. If I then press the right arrow results show up. However the seem to be sorted on the basis of alphabetical order and KDE unlike GNOME doesnt seem to learn what programs I use most often. Also in GNOME I didn't necessarily have to type out enough to narrow results down to one thing or hope that what I wanted would be pointed to. I could also use the arrow keys to select whatever application I wished. With Krunner when I try to arrow my way down to a choice it doesn't let me. I can it turns out move through the results if I start tabbing around but that feels clunky and I only got it after experimentation. It is a far from intuitive or friendly way of doing things.

Barring one or two minor differences in behavior neither Kickoff nor Lancelot are any better. I think KDE would be a lot better from a power user's perspective if it sort of imitated GNOME's dynamic launcher mechanism.  

This effects just about every recent version of KDE that I can think of and isn't dependent on Operating System or Packager. Please look into this. Apologies for the verbose problem description. And finally thank you for all the great work that you have done so far and for what you do have working properly.

Reproducible: Always