Tab-Content won't hide in combat

[Avastos]

Hey guys,

I'm new to wow-addon-development.
Currently I'm learning to create addons for WoW 3.3.5a.

As a base I used this tutorial https://wowwiki-archive.fandom.com/w...tabbed_windows .
Right now the addon has 4 Tabs, in Tab 2-4 are scrollframes (FauxScrollFrameTemplate).

Everything is working fine if the player is not in combat.
If the player enters combat the current tab and its content is "stuck".

For example:
I'm currently reading the content from tab 4 and get attacked (-> enter combat), if i click on another tab, the content from tab 4 will overlay the content from the other tab.
And the content won't update until the combat ist over.


The tab template:

	<Button name="MyTab_Tab" inherits="CharacterFrameTabButtonTemplate" virtual="true">
		<Scripts>
			<OnClick>PlaySound("igMainMenuOpen");
				PanelTemplates_Tab_OnClick(self, My_Mainframe);
				MyAddon_ShowPanel(self, My_Mainframe.selectedTab);</OnClick>
		</Scripts>
	</Button>

The Tabs:

           <Button name="$parentTab1" inherits="MyTab_Tab" id="1" text="Tab 1">
               <Anchors>
                   <Anchor point="CENTER" relativePoint="BOTTOMLEFT">
                       <Offset>
                           <AbsDimension x="50" y="-10"/>
                       </Offset>
                   </Anchor>
               </Anchors>
           </Button>
           <Button name="$parentTab2" inherits="MyTab_Tab" id="2" text="Tab 2">
               <Anchors>
                   <Anchor point="LEFT" relativeTo="$parentTab1" relativePoint="RIGHT">
                       <Offset>
                           <AbsDimension x="-14" y="0"/>
                       </Offset>
                   </Anchor>
               </Anchors>
           </Button>
....

Onload-function

function MyOnload(self)
-- register stuff ...
    self.selectedTab = 1;
    PanelTemplates_SetNumTabs(self, 4);
    PanelTemplates_UpdateTabs(self);
end

ShowPanel-function

function MyAddon_ShowPanel(self, tabNo)
    PanelTemplates_UpdateTabs(self);
    for i = 1,4 do
        g=_G["My_Panel"..i];
        g:Hide();
    end
 
    g=_G["My_Panel"..tabNo];
    g:Show();
    UpdateScrollFrame(Panel2_Scrollframe);
    UpdateScrollFramePanel3(Panel3_Scrollframe);
    UpdateScrollFramePanel4(Panel4_Scrollframe);
end

What I noticed:
The active panel while entering combat will never be hidden.
So every time i checked something like:

if _G["My_Panel"..1]:IsShown() then
        print("Panel is shown")
    end

The frozen panel is always visible.

To make it clear: everything works fine out of combat.

Did I miss something?