Show non-print characters in NetBeans less vividly - netbeans

Question

NetBeans has an option to show non-printable characters, but they are shown with the same vividness as printable characters. This means that a space and a dot are very hard to distinguish: the space is slightly raised, but otherwise visually identical. Many other code editors, and even Gedit, will show non-printing characters greyed out. Is there an option to do this in NetBeans, or do I have to file a bug report?

Answer 1

There is a different (and better) solution compared to my other answer, based on feedback from the OP: download and install the the Editor Whitespace plugin.
Its download page shows that it has not been tested for any version of NetBeans more recent than 8.0, but I have checked that it still works with NetBeans 8.2 and NetBeans 11.2.
To use the plugin:
Click the Download button on the plugin page to install the plugin in some arbitrary location.
In NetBeans: Tools > Plugins > select the Downloaded tab
Click the Add Plugins... button, navigate to the downloaded plugin, click Open, then click Install.
There is no need to restart NetBeans after installing the plugin. Just check the menu option View > Show Non-printable characters to immediately see non-printable characters in source code, excluding line break (¶) characters.
By default the non-printable characters are shown as black dots, but you can use any other color instead:
Tools > Options > Fonts & Colors > Syntax
Select All Languages from the Language drop list, and Whitespace from the Category list. You can select a specific language form the drop list if you prefer.
Using the Foreground drop list, pick the color you want to use to show the dots representing non-printable spaces.
Select Custom... to create your own color if you don't like any of the standard options.
The only benefit to using the plugin is that it suppresses the display of line break (newline) characters, but that is definitely worthwhile. If you have a specific requirement to be able to see line break characters, don't install this plugin, and just use standard NetBeans functionality as described here.

Answer 2

You can change the font color of whitespace characters to any color you want, either for a specific language, or for all languages. Here's how to do it for Java on NetBeans 9:
Tools > Options > Fonts & Colors > Syntax
Select Java from the Language drop list, and Whitespace from the Category list.
Using the Foreground drop list, pick the color you want to use to show the dots representing non-printable spaces. Select Custom... to create your own color if you don't like any of the standard options. As you scroll through the options for Foreground the color of the dots representing printable spaces in the Preview screen change.
Here's a shot showing the color being changed to magenta:
Notes:
The approach described above does not change the color of the line break character at the end of each line, and I don't think that is possible. That is arguably a bug, and at least a missing feature.
Although you can change the Foreground color at any time, it is only relevant when View -> Show Non-printable Characters is checked. Checking that option is also necessary to see the whitespace characters in the Preview screen.
The Background color for Whitespace can also be modified, but the result is invariably ugly and unhelpful.