HighlighterScrollBar: Does not update correctly when scrollbar is invisible

Have the scrollbar setting system-wide set to visible on scroll..

Steps to reproduce:

• have QC open but not at full size (just use clean settings to get default size)
• create a new widget application from template
• current line marker will be visible already at the wrong place, search something inside the open document to highlight some more
• closing and reopening this file or closing QC and reloading the session helps

Second way:

• have a file open that does not fit fully into the QC window's height
• search something to have some search results beside the current line marker
• zoom the content of the file that it fits into the whole QC window
• resize the width of QC

Current result:

• markers stay where they are and do not get updated correctly