docs_devel: update coding sytles (#1042)

* docs_devel: update coding sytles

- Improve readability by splitting sections
- Add link to NetBeans GUi builder manual
- Recommend MVC structure with examples
- Add explanation of API deprecation

Signed-off-by: Hiroshi Miura <[email protected]>

* docs_devel: update coding sytles

- Add sub sub section in GUI design section
- Add warning to check editor generated source

Signed-off-by: Hiroshi Miura <[email protected]>

---------

Signed-off-by: Hiroshi Miura <[email protected]>

docs_devel/docs/30.CodingStyles.md

@@ -2,24 +2,86 @@
 
 OmegaT project uses following coding style rules and coding policy.
 
+## Code Style Basics
+
 * Each java file has a GPL3 copyright header. OmegaT has a unit test to check header.
 * Source code has a maximum 120 characters in each line.
 * The Maximum line length of comments in sources is 80 characters 
 * Indentation is 4 spaces. Don't use TAB character.
 * We don't use asterisk import. You should expand all individual imports.
 * You are recommended to put javadoc comments for all your public methods.
 * We don't set method arguments "final", but you are recommended to treat it as final.
+
+## I18N/L10N/Bundles
+
 * Bundle properties should be ASCII, 7bit clean. All translations should be escaped.
-  * It will change to be UTF-8 after OmegaT version 6.1 beta release.
+  - It will change to be UTF-8 after OmegaT version 6.1 beta release.
+
+## API design
+
 * Stable APIs should be under "org.omegat.core" package.
+* Should not remove API, otherwise, please give `@Deprecation` for old API.
+* Please care for backward compatibility, please mind plugin developers.
+
+## Swing GUI design
+
+* We use a Java Swing technology for GUI parts.
 * GUI parts can be;
-  * written by hand, or
-  * Use NetBeans GUI builder
+  - written by hand, or
+  - Use [NetBeans GUI builder](https://netbeans.apache.org/tutorial/main/kb/docs/java/quickstart-gui/)
 * We don't accept other GUI builder materials;
-  * such as JetBrains IntelliJ GUI builder, JForm Designer, Eclipse Window builder.
-  * If you want, you are recommended to implement it as a plugin.
+  - such as JetBrains IntelliJ GUI builder, JForm Designer, Eclipse Window builder.
+  - If you want, you are recommended to implement it as a plugin.
+
+### GUI programming hints
+
+We encourage developers to take an approach of MVC design.
+
+- You can design GUI parts as View, such as `o.o.g.p.v.AppearancePreferencePanel` class.
+- You can write logics as Controller, such as `o.o.g.p.v.AppearanceContoller` class.
+- Sometimes a custom Model is required for complex design, such as `o.o.g.p.v.PluginInfoTableModel`
+
+### Labels translation
+
+* Please define localized labels got by `OStrings.getString` from bundle.
+* For further maintenance, it is better to make UI components visibility as `package-private`
+  and set its label in Controller class, using a syntax like
+  `Mnemonics.setLocalizedText(ViewClass.uiComponentField, OString.getString("TF_LABEL_FOO"));`
+
+### Source code location to maintain
+
+* Typical UI components are defined;
+
+  - Preference pane contents: classes under o.o.g.preferences.view package
+  - Dialogs: o.o.g.dialogs
+  - aligner: sub-project folder under aligner/src/main/java folder
+  - password dialog for team project: under o.o.c.team2.impl package.
+
+> **Warning**:
+>
+> When UI parts has a comment like
+> ```
+>     /**
+>      * This method is called from within the constructor to initialize the form.
+>      * WARNING: Do NOT modify this code. The content of this method is always
+>      * regenerated by the Form Editor.
+>      */
+>     // <editor-fold defaultstate="collapsed" desc="Generated Code">//GEN-BEGIN:initComponents
+>```     
+>
+> It is generated by NetBeans GUI Editor. You should use the editor to manipulate the file.
+> Please find a file that has same file name but extension is ".form"
+
+## XML parser
+
 * We move XML parser to be StAX based instead of JAXB because of performance.
-  * We use [Jackson](https://github.com/FasterXML/jackson) XML serialization library.
+  - We use [Jackson](https://github.com/FasterXML/jackson) XML serialization library.
+
+## Modules
+
+* We split Machine Translation service connectors, Aligner, Spell Checker driver and
+  dictionary drivers as sub project and build as modules.
+* Modules are installed in "<omegat app root>/modules" instead of "<omegat app root>/plugins"
 
 ## language and characters
 
@@ -28,8 +90,8 @@ OmegaT project uses following coding style rules and coding policy.
 - You should use ASCII characters and 7bit clean for variable names, method names et. al.
 - You are allowed to use String literals in UTF-8 encoding.
 - You should use Bundle for localization strings.
-- You can not use Right-to-Left direction characters in comments.
-- You can not use invisible characters such as non-breakable-space.
+- You can not use Right-to-Left direction characters in comments and code body.
+- You can not use invisible characters such as non-breakable-space and tab.
 - When you need invisible characters in literals, please use unicode escape.
 
 ## Lint check