intellij-sdk-code-samples/topics/basics/faq.md

<!-- Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license. -->

# Plugin Development FAQ

<link-summary>List of plugin development forum topics with frequently asked questions.</link-summary>

This FAQ is a topical index of questions that have been asked (and answered) on the archived
[IntelliJ IDEA Open API and Plugin Development forum](https://intellij-support.jetbrains.com/hc/en-us/community/topics/200366979-IntelliJ-IDEA-Open-API-and-Plugin-Development).
See [](getting_help.topic#problems-with-code-support-issues) on how to post new questions.

> See also [](explore_api.md) for more information and strategies.
>

## Working with XML and XML DOM

> See also [](xml_dom_api.md).

### How do I register a DTD or XSD?

To register a bundled DTD/XSD file, use <include from="snippets.topic" element-id="ep"><var name="ep" value="com.intellij.standardResource"/></include>
for static
or <include from="snippets.topic" element-id="ep"><var name="ep" value="com.intellij.standardResourceProvider"/></include>
for programmatic registration.

## Refactoring

### How can I receive notifications about refactoring events?

[`RefactoringEventListener`](%gh-ic%/platform/refactoring/src/com/intellij/refactoring/listeners/RefactoringEventListener.java)

### How do I show a refactoring dialog programmatically?

[`RefactoringActionHandlerFactory`](%gh-ic%/platform/lang-api/src/com/intellij/refactoring/RefactoringActionHandlerFactory.java)

## Make/Compile

* [How do I get access to class files generated by javac?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206800625-Implementing-a-ClassInstrumentingCompiler-how-to-get-the-generated-class-files)

## Version Control Integration

* [Can I provide line status markers for files in a custom file system?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206791585-Editor-diff-functionality-for-custom-file-system)
* [How do I update the state of VCS actions depending on file status?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206791975-VCS-context-menu)
* [How can I find out the module of a deleted file?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206792195-Module-for-deleted-file-)
* [Can I provide additional decorations for changelists in the Changes view?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206139549-Is-it-possible-to-decorate-change-lists-)
* [How do I report out-of-date files?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206791775-VCS-OpenAPI-what-to-do-with-files-detected-as-out-of-date-)

## Editors, Documents and Files

* [Why doesn't the file change on disk after I changed it through the PSI?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206791625-Action-doesn-t-see-changes-in-xml-file)
* [Can I hook into the file save logic?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206790685-Can-you-tie-into-the-file-save-logic-)
* [Can I mark a part of a file as read-only?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/207042355-Read-only-section-in-editor)
* [How do I control what happens when the user tries to edit such a part?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206791375-Using-locked-regions)
* [How can I show several editors for a single file in tabs?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206795495-Alternative-Editors-ala-HTML-Preview)
* [Can I open an editor which has no underlying file on disk?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206135449-Create-an-Editor-for-a-non-physical-file)
* [How do I highlight elements in a source code editor?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206143909-MarkupModel-navigate-highlighted-elements)
* [How do I allow to navigate between highlighted elements using Find Next?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206143879-HighlightManager-how-to-enable-F3-functionality)
* [How do I get the active editor instance?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206141119-how-to-get-the-Editor-from-PsiElement-)
* [How do I clear the read-only status of a file?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206142039-Clear-read-only-status)
* [How can I show an editor with error highlighting in a tool window?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206146679-Error-highlighting-in-Editors)

## Custom Languages

* [How do I provide auto-popup code completion in my language?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206139359-Autopopup-code-completion-in-custom-language)
* [How do I enable debugging for my custom language which is compiled into Java?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206786875-Debugging-custom-languages-)
* [How do I generate virtual Java classes mirroring the classes of my language?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206143749-Custom-languages-masquarding-as-a-java-source-file-within-IntelliJ)

## User Interface

* [How do I enable file name completion in a combo box?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206139509-Combobox-with-Browse-Button-and-Autocompletion-)
* [How do I provide a custom icon for files/PSI elements?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206143779-Is-it-possible-to-change-icon-of-file-in-Project-view-)

## General

* [How can I implement a custom stack trace analyzer?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206142959-Stack-Analyzer-extension)
* [How do I open a project programmatically?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206146969-how-to-open-a-project-)
* [How do I get the folder of the currently selected file?](https://intellij-support.jetbrains.com/hc/en-us/community/posts/206121889-How-to-get-the-folder-of-currenctly-selected-file)