tdf#143114 Avoid StartDrag on TreeListBox when CaptureOnButton

The original method SvTreeListBox::StartDrag always triggers
a MouseButtonUp event and tries to initiate a Drag of a Line of
a TreeListBox (on MouseMove, btw).

This is not wanted if the last MouseButtonDown started a
ButtonActive mode and activated CaptureMouse, prepared to
trigger Action on that Button on MouseButtonUp. It leads to
unwanted/strange behaviour of Buttons/CheckBoxes when used in
TreeListBoxes.

The behaviour is also dependent on the UI implementation used
under Linux (gen/gtk3_kde5/gtk3/qt5/kf5) which are all
(unfortunately) behaving differently, but a first suggestion/
step to enhance the situation.

Found now for gen/qt5/kf5 that when on the LineEntry, but
not on the CheckBox, on MouseButtonUp the other line gets
switched. Corrected that.

Note: for gtk3_kde5/gtk3 there remains the problem that the
CheckBoxes get switched on MouseButtonDown, butt these are
generic widgets and this needs to be solved differently.

Change-Id: If4cfe894b716185293beff64fc7e482d6f6313d3
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/119644
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@me.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/vcl/inc/svimpbox.hxx b/vcl/inc/svimpbox.hxx
index 554c5a8070ae..c46003c35dd4 100644
--- a/vcl/inc/svimpbox.hxx
+++ b/vcl/inc/svimpbox.hxx
@@ -310,8 +310,17 @@ public:
 
     bool                IsSelectable( const SvTreeListEntry* pEntry );
     void                SetForceMakeVisible(bool bEnable) { mbForceMakeVisible = bEnable; }
+
+    // tdf#143114 allow to ask if CaptureOnButton is active
+    // (MouseButtonDown hit on SvLBoxButton, CaptureMouse() active)
+    bool                IsCaptureOnButtonActive() const;
 };
 
+inline bool SvImpLBox::IsCaptureOnButtonActive() const
+{
+    return nullptr != m_pActiveButton && nullptr != m_pActiveEntry;
+}
+
 inline Image& SvImpLBox::implGetImageLocation( const ImageType _eType )
 {
     return m_aNodeAndEntryImages[_eType];