[enhancement] Change editor background color when LoC changes

[ChrisCarini]

Feedback provided by @harrisjasmine (TL;DR'd):

The widget icon & text are nice, but they are very small and hard to notice while coding. It would be nice to have a more obvious visual indicator to the user that they are reaching the various 'LoC change points'.

[ChrisCarini]

Changing the background might be more difficult than expected; there appear to be 2 ways to change the background:

1. Via a custom theme
2. Via a background image

A custom theme

A custom theme seems to have only static color codes available to set, though perhaps a totally custom UI theme could be created w/ a method to determine the color - look into UITheme

• https://plugins.jetbrains.com/docs/intellij/themes-intro.html?from=jetbrains.org

A background image

A background image seems to be a bit easier, though still difficult. Maybe based on what Yann said in this JB platform thread and using a custom set of background images provided in the plugin resources dir. Eventually calling IdeBackgroundUtil.repaintAllWindows() like in BackgroundImageDialog.doOKAction() (set a breakpoint in doOKAction() on the repaintAllWindows(); call, and see the prop key and value being set.

• https://intellij-support.jetbrains.com/hc/en-us/community/posts/4413373216146-Changing-the-background-color-image-of-a-specific-editor
• https://intellij-support.jetbrains.com/hc/en-us/community/posts/360000228299-Changing-color-schemes-in-entire-IDE-not-just-editor?page=1#comments

[ChrisCarini]

@all-contributors please add @harrisjasmine for ideas, userTesting

[allcontributors[bot]]

@ChrisCarini

I've put up a pull request to add @harrisjasmine! :tada: