Support Dark Theme

[gnl42]

Mylyn doesn't play well with Dark Theme.
It uses hard coded colors that are close to impossible to read in Dark Mode.

An example is TaskScalingHyperlink which uses CommonColors.HYPERLINK_WIDGET

`public class CommonColors {

    public static final Color HYPERLINK_WIDGET = new Color(Display.getDefault(), 12, 81, 172);

    public static final Color TEXT_QUOTED = new Color(Display.getDefault(), 38, 86, 145);

`

(It's worse on my monitor)

[wimjongman]

Patches are welcome.

[BeckerFrank]

What is with the other Color Definitions?
We also have Class org.eclipse.mylyn.internal.context.ui.ColorMap.

[gnl42]

And org.eclipse.mylyn.internal.commons.ui.E4ThemeColor which tries to parse #org-eclipse-ui-workbench-DARK_BACKGROUND as a RGB value:

java.lang.NumberFormatException: For input string: "or" under radix 16 at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67) at java.base/java.lang.Integer.parseInt(Integer.java:668) at org.eclipse.mylyn.internal.commons.ui.E4ThemeColor.getRGBFromCssString(E4ThemeColor.java:57) at org.eclipse.mylyn.commons.ui.GradientColors.getRGBFromTheme(GradientColors.java:211)

"Fixed" by #298

[gnl42]

I could use suggestions/pointers on how to go about doing this.

I have no experience with SWT UI programming. Trying to make sense of the various articles on Eclipse themes but unsure how to actually apply them..

Are custom colours really needed? Or are Eclipse defaults good enough?

[wimjongman]

Are custom colours really needed? Or are Eclipse defaults good enough?

When possible, Eclipse defaults would be the way to go.

https://www.vogella.com/tutorials/Eclipse4CSS/article.html contains many clues, but you probably already found it.

Theming is based on CSS, and when the plugin spy is installed, you can use CTRL+ALT+SHIFT+F6 to see how the component is styled.

Please ask specific questions and I will help.