I had two application being debugged - an ordinary application and tomcat.
When i decided to restart the ordinary application i clicked "stop", it stopped, but "run" button was still gray. I just started another ordinary application from toolbar and it started.
Then I decided to restart Tomcat, and "run" button also stayed gray after tomcat stopped.
I tried to start tomcat one more time (it was chosen in toolbar, but when I pressed "run" it actually ran the ordinary application, not tomcat. If I click any run configuration, it didn't react - tomcat was still chosen.
At last i could start tomcat, but the debugger UI was broken. "Debugger window" contained "variables" and "watches", and console and frames were in separate tabs. If I clicked console, it would appear for a moment, then disappeared again. "Frames" and "debugger" tabs were still choseable.
The ordinary application debugger UI was also broken. It had variables, watches and console on the same debugger tab and frames in another tab. But when I tried to bring console to separate tab I got
Error during dispatching of java.awt.event.MouseEvent[MOUSE_RELEASED,(1213,711),absolute(1209,707),button=1,modifiers=Button1,clickCount=1] on frame0
java.lang.AssertionError
at com.intellij.debugger.ui.content.newUI.NewDebuggerContentUI.findCellFor(NewDebuggerContentUI.java:248)
at com.intellij.debugger.ui.content.newUI.actions.BaseDebuggerViewAction.isDetached(BaseDebuggerViewAction.java:9)
at com.intellij.debugger.ui.content.newUI.actions.MoveToTabAction.update(MoveToTabAction.java:15)
at com.intellij.debugger.ui.content.newUI.actions.BaseDebuggerViewAction.update(BaseDebuggerViewAction.java:10)
at com.intellij.openapi.actionSystem.AnAction.beforeActionPerformedUpdate(AnAction.java:210)
at com.intellij.ui.tabs.JBTabs$ActionButton.actionPerformed(JBTabs.java:21)
at com.intellij.ui.InplaceButton$1.execute(InplaceButton.java:3)
at com.intellij.util.ui.BaseButtonBehavior$MyMouseListener.mouseReleased(BaseButtonBehavior.java:96)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:272)
at java.awt.Component.processMouseEvent(Component.java:6038)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
at java.awt.Component.processEvent(Component.java:5803)
at java.awt.Container.processEvent(Container.java:2058)
at java.awt.Component.dispatchEventImpl(Component.java:4410)
at java.awt.Container.dispatchEventImpl(Container.java:2116)
at java.awt.Component.dispatchEvent(Component.java:4240)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
at java.awt.Container.dispatchEventImpl(Container.java:2102)
at java.awt.Window.dispatchEventImpl(Window.java:2429)
at java.awt.Component.dispatchEvent(Component.java:4240)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at com.intellij.ide.IdeEventQueue.c(IdeEventQueue.java:172)
at com.intellij.ide.IdeEventQueue.b(IdeEventQueue.java:62)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:108)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
and no reaction from GUI. The button "Blame IDEA core" was disabled, though the stack was there and the error was caught.
I could send variables and watches to separate tabs and after I did that I could send console to separate tab and the UI was usable again.
But "stop" buttons were still disabled in the left side of the debugger, though applications were running.