Description:
When I open a new file or a new window it will open in a new tab instead. The result is OK if there are not any problem. But when open a new window in a new tab instead, The tab header (which contained file's name or window's name) will obscure the first row of toolbar icon. It won't obscure if use fullscreen only.

Steps to Reproduce:
1.Open the first file.
2.Open another file


Actual Results:  
You cannot approach the 1st row icon if you don't use full screen window. If use full screen, no problem found.

Expected Results:
I don't use full screen. So I want to approach all icon.


Reproducible: Always

User Profile Reset: No

Additional Info:
[Information automatically included from LibreOffice]
Locale: en-US
Module: SpreadsheetDocument
[Information guessed from browser]
OS: Mac OS X (All)
OS is 64bit: no

If it still be like this, please give a choice to choose " open new file in new tab or new window" in Preference. 
Builds ID: LibreOffice 5.4.2.2


User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Safari/604.1.38