I often switch between English and Hungarian while typing, and it would be inconvenient to swap keyboard layouts mid-sentence as many the keys are in different places and I can't memorize them all. I realize that OS X has the "press-and-hold" special character feature, but this feature doesn't contain all the Hungarian letters when using the English keyboard layout. In Yosemite, it was possible to edit the .plist file that governed which characters appear in the press-and-hold menu. However, when I installed El Capitan, it got reset to defaults, and now to change it I need to disable rootless, which is a pain considering that I'll have to do this all over again soon when installing Sierra. I can easily type í, ú and é because I can press Alt+E and then press any letter and it will give it an accent. I can also type ü and ö easily with the same method with Alt+U. But there is no such function for double accents like ő and ű that I'm aware of. Any way to change this? I tried using substitutions which can be set up in System Preferences, so that it would substitute o'' with ő. Strangely, it works for ő and Ő, but it doesn't work for typing a lowercase ű. It always becomes an uppercase Ű even though I have set up substitutions correctly, seems like a bug. Also, this method gets ignored in Photoshop and many other non-standard apps. The "Emoji & Symbols" viewer that appears when pressing Ctrl+Cmd+Space doesn't always work in every app either. For example, Photoshop and many other apps don't support the Emoji & Symbols viewer. Basically there are countless ways to do this in theory, but none of them work reliably in practice in all apps and all circumstances. It's as if OS X was trying very hard to make it impossible to type these special characters. So I want a quick and reliable way to type the letters ő and ű while using an English keyboard layout. Currently I have to Google a Hungarian website, hunt for a word with the letter I need in the required case, and copy paste it. It's not fun. Any ideas? Any small apps? It would be nice to press a key combination and have it type the desired letter, or something like that. Thanks.