Microsoft Office 2003 had this but was taken away in later Microsoft Office versions. I find it very useful. I would love LibreOffice to have this feature. Basically in Microsoft Office 2003 I would go to the insert menu and click on International character toolbar and change the language to Spanish. If I was typing in Spanish I would go to the toolbar and click on the symbol I needed for that certain document and it will insert it. I would also hold shift if I wanted it capitalized.
Please add this feature in a future version of LibreOffice. Thank you.