This is an edited version of the following idea: https://feedback.unity3d.com/suggestions/show-waitcursor-while-unity-processes-changed-script
While I totally agree with the idea of giving the user a more prominent feedback when scripts have been compiled (and he can then press the Play button again), I would rather like to see a red bar on the right bottom corner while the scripts are being compiled, and a green bar when it has been completed.
This way the user immediately notices that the work is done, and it's yet such a minimal optical interference that it won't annoying him.
This is the original idea description:
If you're a programmer, you'll find yourself constantly switching from Visual Studio to Unity to change scripts.
When you've changed the script, Unity takes a while to process the changed script.
During this processing, Unity shows no visual feedback.
One finds himself clicking on the UI buttons (like "Projects", "Console", "Clear" or any other button in the Unity Editor) to find out if Unity has finished processing.
An easy solution to this problem would be to simply show a prominent visual feedback while Unity processes the edited script and another prominent visual feedback when the processing is done.
This would help programmers to quickly see when Unity has finished processing the script.