Very cool icon, but you might want to replace that "Strg" key with one that appears on more keyboard layouts. I've only ever seen Strg keys on German keyboards1. Using another key would make it more recognizable to more people, I think.
Maybe Alt?
Funny, now that you mention it, I have been wondering for many years why the "control" key is not labelled "control" on PC keyboards... buf of course I haven't used an English keyboard in a decade, so I wouldn't remember 
Heh

. Germans and their translations

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I've heard of such a thing as a Dutch keyboard layout, but as far as I'm concerned that's just the most annoying thing ever to happen to my Windows keyboard settings.
Dead keys are evil, especially when programming in languages that use ' and " as delimiters for character/string constants

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Macintosh calls it "control", I think.
During the Google searches I did to investigate for that post
1, I saw mac keyboards with both "Ctl" and "Ctrl". Didn't see any "Control" though. And I wouldn't know from personal experience, given that I've only used macs like two times (both > 5 years ago) in my entire life.
1) Before I noticed that Strg was Ctrl, not Shift. (I initially wanted to recommend Ctrl or Alt for use in the icon)