How can I have a dash-like search under Xfce?

If you don't like the xfce-appfinder, you can replace it with another offering from the application store. synapse is a very capable example. Then assign the Alt+F2-shortcut to it.

I guess your best bet is to use any of the following two recentish plug-ins:

• xfce4-whiskermenu: "Whisker Menu is an alternate application launcher for Xfce. [..] You can browse through all of your installed applications by clicking on the category buttons on the side. [..] Additionally, Whisker Menu keeps a list of the last ten applications that you’ve launched from it. [..] If you’re not sure exactly where a program is listed, instead of browsing through each category you can simply enter a search term. The search field is focused when opening the menu, so you can just start typing."

  To me this plug-in recalls the Windows 7-style Start button. There are several PPAs (including this PPA) that provide it for easy installation.

  

• xfdashboard: "Maybe a Gnome shell like dashboard for Xfce"

  It comes with extensive documentation and screenshots.

  

To access the Xfce4 Terminal from the Alt+F2 screen, one has to type

xfce-terminal

and then click the Execute button. See how over here: http://docs.xfce.org/apps/terminal/getting-started (but note that typing Xfce Terminal as mentioned in the link may not work whereas xfce-terminal will).

To know more about the two modes of the Alt+F2 screen, take a look at http://docs.xfce.org/xfce/xfce4-appfinder/usage.

As far as Writer is concerned, my guess is that you'll have to type

libreoffice3.6 --writer

or

libreoffice --writer