In KDE 3.5, I could drag a binary of an application, or even a .sh script, from Konqueror (the file manager) into the task bar, and immediately a working button to launch the application was available in the taskbar (=panel). Alternatively, it was easy to make a button to start any application by just typing the name, choosing an icon, and done. This allowed even dragging the .sh file to launch a Java app in one go into the taskbar and it WORKED, something even Gnome can't do (and is hell in KDE 4.X to do apparently).

In KDE 4.X, I haven't yet found an easy way to make such an app launching icon. I only found a sort of way which involved creating a .desktop file somewhere first, but this is a real hassle, you need to maintain a directory of .desktop files yourself somewhere, and editing anything about the launch icons (such as the icon image itself, extra command line parameters, the name, ...) by right clicking on them seems to be impossible or really hidden.

Is there any way in KDE 4.X to get something in a panel/taskbar to easily have application launcher icons, just like it was in KDE 3.5, and is in Windows?

Drag and drop to panel works fine here (4.4.2, but worked in earlier versions as well). Yes, even .sh files.
Just make sure that you widgets are unlocked.

What widget do you use for this? Mine is called Quicklaunch, it's in KDE 4.3, and drag and drop doesn't work.

EDIT: now it turns out... Drag and drop works to the panel, but not to the quicklaunch! What is the point of the quicklaunch widget?

Aardwolf wrote:EDIT: now it turns out... Drag and drop works to the panel, but not to the quicklaunch! What is the point of the quicklaunch widget?

Well, the basic difference is:

1. Icons dragged to the panel are always full-height in the panel.
2. Quicklaunch, on the other hand, can be configured to divide the icons up in several rows.

Note though that the quicklaunch widget is easier to use in 4.4. You can just right-click on it to bring up a menu where you can add launchers (using a mini-version the menu), and sort them. IIRC this was not present in 4.3.