I run a VNC client (tightvnc) along with other applications on a Windows machine. Inside my VNC session, I typically have several xterms and gvim windows open. How can I switch between the applications within VNC? If I do ALT-TAB, that results in switching between the applications in Windows where the whole VNC is considered as a single application; I do not want that. Is there some way to configure some key bindings, any two/three keystroke is okay for me, to do the job?
You should be able to modify the keyboard shortcut assigned to switching windows on the VNC server side desktop. You didn't specify what desktop environment you are using but on my computer (Ubuntu 10.10 with Gnome) this is the Keyboard Shortcuts control panel from the System menu (System > Preferences > Keyboard Shortcuts).
The Alt-Tab function is near the bottom (under "Window Management", labelled "Move between windows, using a popup window"). Change it from Alt-Tab to something that isn't a shortcut on either your Windows computer or the apps you're using on the VNC server side.
This probably does belong on SuperUser, but, here's a solution.
I use the vnc viewer from TightVNC (so, this might not work on all vnc viewers). On the tool bar at the top of the vnc viewer window there is an ALT modifier button. Click that (it should remain pressed). Then, just press tab. Once you've got the window you want, click the alt button again to un-press it.
Both the TurboVNC and TigerVNC viewers support keyboard grabbing, which will allow you to send Alt-Tab and other special keystrokes to the VNC server. TurboVNC evolved from the TightVNC 1.3.x code base originally, so it maintains full backward compatibility with all of the TightVNC 1.3.x features (but it also has many new features and fixes relative to TightVNC 1.3.x.) TigerVNC was based on RealVNC originally, so it does not have 100% coverage of the TightVNC features, but it and TurboVNC share similar encoding techniques. Both implement a variant of Tight encoding that is tuned for high performance. If you are using Windows as a client, then TurboVNC's GUI for that platform is generally nicer than TigerVNC's (the TurboVNC Windows viewer still has the same basic look & feel as the TightVNC Windows viewer.)
Try Remmina! See there: http://www.brianodonovan.ie/2012/02/remmina-is-best-linux-application-for.html
The AltTab is an example of a key combination which could be interpreted by your local operating system or by the remote operating system.
As you say, AltTab will by default switch focus from Remmina to another local application on your laptop. If you want to use AltTab to switch between applications on your remote Windows system then you need to select the option "grab all keyboard events" (there is an icon at the top of the Remmina screen to enable/disable this).