Switching between windows while typing impossible


I have problem with LibreOffice ( on Ubuntu 14.04 LTS. When I am typing something in Calc in a cell, I do want to switch over other documents (e.g. a Writer document) to check what is there. Then I come back to Calc windows to continue writing. For switching between windows I use Alt-Tab combination.
The problem is that if I switch between LibreOffice Calc and other softwares, then I can continue writing in the cell, as it remains active. However, if I switch between LibreOffice Calc and Writer, then the cell becomes inactive. Typing will then replace previous content. A user in this case expects to continue to type. Do you think, there is an option for this, or is this a bug?