"Change Start Message" option not working correctly.

[DahliaSR]

Describe the bug
The option does work as expected, when multiple tabs are used at the same time, but only, if
tab focus is changed via mouse click.

When using only one tab, focus change via mouse click, does insert the starting message of the new tab,
but the starting message of the previous tab is not beeing removed.

The option does have no effect, if tab focus is changed via the tab buttons only.
Neither is the starting message of the new tab inserted, nor does the starting message of the previous tab get deleted.

Minecraft Info
Minecraft information:

• AdvancedChatHUD 1.3.2

Expected behavior
With the "Change Start Message" option enabled, changing focus from a tab to another should remove the start message
of the previous tab from the input line and insert the start message of the now active tab.
Neither the number of visible tabs, nor the way focus is changed (tab buttons or mouse click) should cause different behaviour of the
feature.