Holding the RMK down over almost any part of Konqueror's window will bring up an appropriate menu.
RMK on any free area of the Titlebar brings up the Titlebar Menu, allowing you to control the position of Konqueror's window as well as the decoration applied to all KDE program windows.
RMK on any free area of the Toolbar to bring up the Toolbar Menu. You can use it to control whether the Toolbar is at the top, bottom, left or right of Konqueror's window or is a separate floating object. You can also use the Toolbar Menu to set the size of the buttons on the Toolbar, and whether they are shown as icons, text or both.
If you have the Bookmarkbar showing, then RMK on any free part of it to bring up the Bookmarkbar Menu which lets you change its position and whether items are shown as text, icons, or both.
If you RMK on any free area of a view then you will get this menu, which contains the Up, Back, Forward and Reload navigation commands as well as the "Create new" option from the Bewerken menu.
This is a most useful feature, as RMK on the name or icon of any file or directory not only "selects" that item but also brings up a menu allowing you to Cut, Copy or Remove the item in various ways, add it to your Bladwijzers, open it with the program of your choice or preview it, or edit the file type or properties.
RMK on the Status Bar at the bottom of a window or view, to add or remove a view within Konqueror's window.