I recently was forced to notice a pretty annoying problem in Chrome (tested with 51.0.2704.103 and the newest 51.0.2704.106 (64-bit)) in full screen mode under El Capitan (10.11.5 (15F34)).
By default the tab, address and bookmarks bar are hidden in full screen mode, which is fine as it gives more screen estate. To make them visible one can use ⌘L but of course if you're using the mouse it's more convenient to just bump the mouse to the upper edge. The difference to ⌘L is though that this also shifts in the menu bar. This wouldn't be a problem (and is even desired if you want to use the menu) but when I move the mouse down again to a certain threshold (just below the tabs/title bar) the menu bar scrolls back after half a second or so and with it the button or whatever I try to press (e.g. when I try to press the "back" button I end up pressing the "Apps" button in the bookmarks bar below.)
Other applications just keep the menu bar until the mouse is moved back to the main view area, so you can take your time to use whatever button/toolbar you want without getting it shifted away in the middle of a click. (Or they display the menu bar as an overlay, so there is no shifting at all.)
I hope I could describe the problem in an understandable way. Otherwise you might just try it out in Chrome yourself. I'm pretty sure the problem wasn't there before until recently.