Marquee selection should have rectangular corners

[timothyis]

Not possible to remove border-radius on electron windows right now, but the cropping/marquee selection area should not have a border-radius.

[sindresorhus]

Here's the relevant Electron issue: electron/electron#414

[sindresorhus]

We could also add a margin to the cropper. Like this:

--- a/app/src/renderer/css/cropper.css
+++ b/app/src/renderer/css/cropper.css
@@ -1,9 +1,12 @@
 @import 'eightpoint/dist/eight.min';

 html, body, .content {
-  width: 100%;
-  height: 100%;
-  overflow: hidden;
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  margin: 3px;
 }

But then we need to take that into account for all our calculations.

[skllcrn]

Another possible temporary solution, pending a potential rewrite of the cropper @sindresorhus?
electron/electron#414 (comment)

[albinekb]

It's the same kind hack, we'd need to take those size differences in mind when calculating 🙁

[skllcrn]

Closed via #494