For some odd reason AdBlock Plus in Thunderbird choose to use the keyboard CTRL+SHIFT+V to open the sidebar (blockable items). The problem with using this is CTRL+SHIFT+V is the universal keyboard shortcut to Paste as Plain Text of Paste without Formatting. After some searching I found a thread from October 2012 on the Adblock Plus Forums that provided a solution: From within Thunderbird go to Tools > Options > Advanced (OS X: Thunderbird > Preferences… | Linux: Edit > Preferences) and then click the Config Editor… button in the lower right of the Options/Preferences Window. If needed click the I’ll be careful, I promise…