unfolding/folding groups via mouse click in tree often moves group out of view

[westram]

Reproduce (difficult; depends on really many settings/circumstances)
Best approach:

• switch to dendrogram view
• use the to unfold or fold a group which is (much) bigger than viewport (when expanded)
• group is moved outside the viewport (normally somewhere above)

Proposed "fix":

• when clicking a clade ⇒ remember node
• after refresh:
  check whether the group handle has been displayed in viewport.
  IIRC this is already done for 'selected group/species'.
• if group handle was not displayed in viewport
  ⇒ center on group (same as JUMP button)

Workarounds (after group vanished from viewport):

• use JUMP button
• press ENTER twice

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This misbehavior was previously documented in #748 (as similar but probably unrelated). IRS view is affected as well, but has general, systematic positioning problems.

[westram]

• was reported to behave correct in [18660]
• first report of misbehavior on 2021-Oct-11 (i.e. before [18789])