Total Commander

This bug first mentioned here without reproduce steps. So they are below.

Reproduced with empty ini (with the only custom option to show tabs in multiple lines to reach full empty space disappearance). Should be possiblle to reproduce different TC window sizes (tested default 924 x 668 and maximized 1024 x 742), number of button bar lines also shouldn't matter.

To reproduce:
1. Open TC with fresh ini as settings file.
2. Go to Configuration->Layout->Folder tabs, enable Tabs on multiple lines, press OK.
3. Open in both panels some folder with long name and many folders/files inside (more than panel shows). I used c:\Program files\.
4. Scroll to the end of opened folder in both panels, so both sliders in scrollbars will reach the bottom (you can use End key on keyboard to do it quickly).
By default TC starts in full view, and here I can see empty space after last file with vertical size like file cursor's one. It's possible to press and hold right mouse button on that space to open context menu of opened folder.
5. Focus (put file cursor) on last file in left panel, so it will be easy to see how empty space will change in next steps.
6. In left panel, open one new tab of your folder (Ctrl+T on keyboard), now you have 1st line of tabs.
Empty space behind last file of left panel will be smaller, but still present.
7. Open in left panel new tabs (Ctrl+T on keyboard) and stop when you'll get 2nd tabs line.
Now empty space behind last file in left panel completely disappeared.
8. (bonus) Move panel splitter (left edge of vertical bar) from left to right so you'll get 1 line of tabs in left panel again. Now small empty space (as in step 6) appears again behind last file.

I have the .. entry on top enabled
and the context menu for the current dir is available on this entry.
So there is no need for any empty space in this case.

Also a short right-click on the empty space in the right side of the the Current directory bar above the filelist wil show the context menu for the folder itself. (A long right-click shows the panel history). So no need for the empty space to click on.

In email Christian Ghisler explained such behavior:

Christian Ghisler wrote:This empty space is just appearing when the height of the listbox control isn't an even multiple of a single listbox item. When you add tabs, the space for the listbox shrinks, so the height of the listbox changes. Since the height of a tab isn't the same as the height of a single listbox item, the remaining space after all the items changes.

He didn't write whether he will (or it's even possible to) change it.

I can say that empty space behind filelist is a most intuitive place to look with intention to drag files or call a context menu.

DrShark wrote: ↑2019-03-24, 20:19 UTC In email Christian Ghisler explained such behavior:

Christian Ghisler wrote:This empty space is just appearing when the height of the listbox control isn't an even multiple of a single listbox item. When you add tabs, the space for the listbox shrinks, so the height of the listbox changes. Since the height of a tab isn't the same as the height of a single listbox item, the remaining space after all the items changes.

He didn't write whether he will (or it's even possible to) change it.

I can say that empty space behind filelist is a most intuitive place to look with intention to drag files or call a context menu.

For me is searching for an empty space not very intuitive.
My method or Petermans is much easier to do.

I cannot change it because you cannot add empty space to listboxes. I could add an extra entry which shows nothing, but this could cause other problems (e.g. the item could be selected).

ghisler(Author) wrote: ↑2019-03-25, 09:02 UTCI could add an extra entry which shows nothing, but this could cause other problems (e.g. the item could be selected).

You can add it as [.] entry (similar to [..] on top). Currently for [..], which is an alias to a parent directory, TC opens context menu of currently opened directory (which is a subdir of parent one), this is wrong by design anyway.
Of course option to show [.] below the list should be disabled by default so current UX with only [..] one visible won't change.
However, if option to show [.] is enabled, [..] should show context menu of parent dir, and [.] - for currently opened. Also Enter on [.] may be a drop target to currently opened dir, refresh it with Enter/LMBDblclick, show its properties with Alt+Enter (would be especially useful to see properties of empty or name-encrypted archives.)