TYPO3 Core

These days I upgraded a 4.2.12 installation to 4.3.2. Everything worked fine in 4.2.12.
But now the menu doesn't work any more. It's a TMENU_LAYERS and is not usable any more in FF3.6. It behaves like this:
When moving the mouse pointer over an entry of the first level, the list of entries at the second level is displayed. This works fine. But when moving the pointer into this box and so leaving the main entry, the menu box disappears. Although the pointer is already in it.

This behaviour only occurs in FF3.6, not in FF2, FF3.0 or IE.
And it only occurs in TYPO3 4.3.2. When switching back to 4.2.12 the problem disappears. Upgrading again to 4.3.2, it's there again.
So now I have to stay at 4.2.12 until this bug has been fixed.

The Typoscript of the menu:

includeLibs.tmenu_layers = media/scripts/tmenu_layers.php

temp.2010.navigation.menu= HMENU
temp.2010.navigation.menu {

excludeUidList = 190,17

1 = TMENU_LAYERS
  1 {
    wrap = <div id="main-menu"><table border="0" cellpadding="0" cellspacing="0"><tr>|</tr></table></div>

layerStyle = position:absolute; visibility:hidden; background: #8bc03f;
    hideMenuWhenNotOver = 1
    hideMenuTimer = 250
    expAll = 1
    leftOffset = 50
    topOffset = 24
    relativeToTriggerItem = 1

NO.allWrap = <td class="level1 level1-no">|</td>
    ACT = 1
    ACT.allWrap = <td class="level1 level1-act">|</td>
  }
  2 = TMENU_LAYERS
  2 {
    wrap = <div class="sub-menu1">|</div>

layerStyle = position:absolute; visibility:hidden; background: #8bc03f;
    hideMenuWhenNotOver = 1
    hideMenuTimer = 250
    expAll = 1
    leftOffset = -1
    relativeToTriggerItem = 1
    relativeToParentLayer = 1
    relativeToTriggerItem.addWidth = 1

NO.linkWrap = <div class="level2 level2-no level2-first">|</div> |*| <div class="level2 level2-no level2-middle">|</div> |*| <div class="level2 level2-no level2-last">|</div>
    IFSUB = 1
    IFSUB.linkWrap = <div class="level2 level2-no level2-sub level2-first">|</div> |*| <div class="level2 level2-no level2-sub level2-middle">|</div> |*| <div class="level2 level2-no level2-sub level2-last">|</div>
    ACT = 1
    ACT.linkWrap = <div class="level2 level2-act level2-first">|</div> |*| <div class="level2 level2-act level2-middle">|</div> |*| <div class="level2 level2-act level2-last">|</div>
    ACTIFSUB = 1
    ACTIFSUB.linkWrap = <div class="level2 level2-act level2-sub level2-act-sub level2-first">|</div> |*| <div class="level2 level2-act level2-sub level2-act-sub level2-middle">|</div> |*| <div class="level2 level2-act level2-sub level2-act-sub level2-last">|</div>
  }
  3 = TMENU
  3 {
    wrap = <div class="sub-menu2">|</div>

noBlur = 1
    NO.linkWrap = <div class="level3 level3-no level3-first">|</div> |*| <div class="level3 level3-no level3-middle">|</div> |*| <div class="level3 level3-no level3-last">|</div>
    ACT = 1
    ACT.linkWrap = <div class="level3 level3-act level3-first">|</div> |*| <div class="level3 level3-act level3-middle">|</div> |*| <div class="level3 level3-act level3-last">|</div>
  }
}
(issue imported from #M13890)