Richtext editor freezes Capella 7.0.0 on Linux

[MoritzWeber0]

In the latest pre-release of Capella 7.0.0, the description editor / richtext editor is completely unusable. Whenever I start typing, Capella freezes completely.

Steps to reproduce

1. Install the latest 7.0.0 Capella bundle on Linux
2. Start Capella
3. Create any element that has an description
4. Open the description field in the Properties tab. It takes a few seconds to load. Then start typing at least two characters and Capella will freeze.

I can also provide a Docker image to reproduce. Let me know if that would help.

Stacktrace

SWT call to Webkit timed out after 10000ms. No return value will be provided.
Possible reasons:
1) Problem: Your javascript needs more than 10000ms to execute.
   Solution: Don't run such javascript, it blocks Eclipse's UI. SWT currently allows such code to complete, but this error is thrown 
     and the return value of execute()/evalute() will be false/null.

2) However, if you believe that your application should execute as expected (in under10000 ms),
 then it might be a deadlock in SWT/Browser/webkit2 logic.
 I.e, it might be a bug in SWT (e.g this does not occur on Windows/Cocoa, but occurs on Linux). If you believe it to be a bug in SWT, then
Please report this issue *with steps to reproduce* via:
 https://bugs.eclipse.org/bugs/enter_bug.cgi?alias=&assigned_to=platform-swt-inbox%40eclipse.org&attach_text=&blocked=&bug_file_loc=http%3A%2F%2F&bug_severity=normal&bug_status=NEW&comment=&component=SWT&contenttypeentry=&contenttypemethod=autodetect&contenttypeselection=text%2Fplain&data=&defined_groups=1&dependson=&description=&flag_type-1=X&flag_type-11=X&flag_type-12=X&flag_type-13=X&flag_type-14=X&flag_type-15=X&flag_type-16=X&flag_type-2=X&flag_type-4=X&flag_type-6=X&flag_type-7=X&flag_type-8=X&form_name=enter_bug&keywords=&maketemplate=Remember%20values%20as%20bookmarkable%20template&op_sys=Linux&product=Platform&qa_contact=&rep_platform=PC&requestee_type-1=&requestee_type-2=&short_desc=webkit2_BrowserProblem
For bug report, please atatch this stack trace:
java.lang.Throwable: 
	at org.eclipse.swt.browser.WebKit.getStackTrace(WebKit.java:300)
	at org.eclipse.swt.browser.WebKit.getInternalErrorMsg(WebKit.java:293)
	at org.eclipse.swt.browser.WebKit$Webkit2AsyncToSync.execAsyncAndWaitForReturn(WebKit.java:1272)
	at org.eclipse.swt.browser.WebKit$Webkit2AsyncToSync.runjavascript(WebKit.java:1030)
	at org.eclipse.swt.browser.WebKit$Webkit2AsyncToSync.evaluate(WebKit.java:1000)
	at org.eclipse.swt.browser.WebKit.evaluate(WebKit.java:1299)
	at org.eclipse.swt.browser.WebBrowser.evaluate(WebBrowser.java:406)
	at org.eclipse.swt.browser.Browser.evaluate(Browser.java:665)
	at org.eclipse.swt.browser.Browser.evaluate(Browser.java:614)
	at org.eclipse.nebula.widgets.richtext.RichTextEditor$3.completed(RichTextEditor.java:284)
	at org.eclipse.swt.browser.WebKit.lambda$7(WebKit.java:1769)
	at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:40)
	at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:132)
	at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:5040)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4520)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1155)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1046)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:643)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:550)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:171)
	at org.polarsys.capella.core.platform.sirius.ui.app.CapellaApplication.start(CapellaApplication.java:118)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:203)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:136)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:402)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:659)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:596)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1467)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1440)

 Additional information about the error is as following:
 The following javascript was executed:
function SWTWebkit2TempFunc1(){initEditor();}; SWTWebkit2TempFunc1()

I've tried several different webkit2gtk versions, also different distributions (Alpine, Fedora & Debian). I could reproduce the issue in all cases.

The issue seems to be different to the other reported issues affecting Capella versions < 7.0.0 on Linux: https://github.com/eclipse-capella/capella/issues/2316