ToolTips leave windows on Linux

[kasemir]

When display builder tool tips are enabled, we've seen them leave windows behind on Linux.

Sometimes these windows contain a snapshot of the display, but in most cases they are transparent/invisible.
They have the size of the tool tip, they remain on top of the screen, and they prevent mouse clicks from reaching whatever's behind.

The typical example: A button suddenly stops being clickable. Moving the display such that another widget is at the previous button location, that widget becomes non-clickable.
Move some other non-CSS program window there, and that same screen region is non-clickable in whatever program window you place there.

Exiting CSS fixes those dead screen regions.
The affected region has the typical size of a tool tip, so the assumption is that this is indeed an X11 window created for the tool tip and then left behind.
Seems to only happen with JavaFX tool tips when running inside the SWT FXCanvas.

As a workaround, the display builder has been updated. Setting -Dorg.csstudio.display.builder.disable_tooltips=true disables tool tips.

[claudio-rosati]

@kasemir
Is that behaviour existing also on the Phoebus version of Display Builder?

[kasemir]

Haven't seen it while working on phoebus, and just starting to use it on beam lines.

Also haven't seen a problem with SWT tool tips. I somewhat hope that the problem is related to the SWT FXCanvas hosting of the JavaFX tool tips, and won't happen with plain JavaFX.
But just in case, Phoebus supports the same -Dorg.csstudio.display.builder.disable_tooltips=true to disables tool tips.

[claudio-rosati]

I don't have any reported problems about tooltip, and I cannot reproduce it by myself.
At ESS we use CentOS 7.5

[claudio-rosati]

See also JDK-8165762

[kasemir]

We use RHEL 7. The problem was first observed on a machine that used Synergy to share one mouse & keyboard with other computers, so we assumed it could be a side effect of moving the mouse over to another computer. But now we've seen it on a single computer, dual monitor setup.