UPDATE: This seems to not work anymore. See Comments…
As the qtranslate plugin doesn’t seem to be updated anymore, i switched to mqtranslate, which is a fork of qtranslate but compatible to newer versions of WordPress.
Unfortunately, with WordPress Version 4, mqtranslate seems to have some problems with the visual editor. One particularly bizarre one encountered to me yesterday:
Step 2: Find Line 292, which should read like this:
Step 3: Comment this line out with 2 slashes (/), so that it reads like this:
Step 4: Save the file and upload it again to your mqtranslate plugin folder
Step 5: Done! The visual editor should work correctly again.
Please let me know if i could help you or if other problems occur after you applied the fix.