How to grab a webpage with an open drop-down menu?
Solution 1:
You can use this application called shutter
Alternatively run the following to install the package via a terminal (Default keyboard shortcut: CtrlAltT)
sudo apt-get update && sudo apt-get install shutter
It has options to capture dialog boxes, tooltips and pretty much everything that you will ever encounter or need to take a screenshot of.
To capture a drop-down menu with Shutter, open Shutter after installing it and click on the button pointed by the arrow in the screenshot below:
After clicking, you'll have a timeout before you which you can select a drop-down, keep the drop-down clicked until the timeout finishes to capture the selected drop-down menu
After capturing, click on Export button to either save the file to your desktop or host it on an image hosting service or FTP it or even push it to your Ubuntu One account.
You could also set a timeout and click the Window button and choose your browser from the dropdown. Before the timeout reaches 0, select the drop-down in the site to take a screenshot of the drop-down menu along with the website open.
Solution 2:
gnome-screenshot should work - but you can try Xfce4-screenshot that works very well for me.
Set a delay before capturing, do not forget to click ok and then drop down the menu and leave it open until delay ends.
You will get more than just the menu. You will have to use another application like gwenview to limit the selection to just the menu, if that is all you want.
Solution 3:
I was having this same issue and got it working with gnome screenshot. The key was to make sure 'Capture the mouse pointer' is selected and make sure it grabbed the full screen instead of just the window.