You never said what software you're using...

Keywords: (none) => NEEDINFO

Sorry; I assumed Cauldron and "open any window" was enough; but I missed KDE/Plasma -- otherwise a default install.  It happens on Firefox, emacs, konsole, claws-mail, etc.   It doesn't matter what application, it's the window that has the problem.  
Operating System: Mageia 9
KDE Plasma Version: 5.23.4
KDE Frameworks Version: 5.88.0
Qt Version: 5.15.2
Kernel Version: 5.16.14-server-1.mga9 (64-bit)
Graphics Platform: X11
Processors: 20 × 12th Gen Intel® Core™ i7-12700K
Memory: 62.5 GiB of RAM
Graphics Processor: AMD Radeon RX 6600 XT

> The only workarounds are:
> - move the window if not maximized
> - if maximized, restore and likely still have to move the window
So? Is this not just normal management of windows?

You have missed some other things: right-click the window title bar, and the menu usually offers a 'Resize' option. Admittedly with limited powers, most often not being able to move the bottom window edge, which can really matter.
Also, unless Alt has been re-assigned, pressing it allows you to move a window whose border you cannot see or grab.
Also, windows can normally be moved slightly off-screen to grab the edge you want.

I am writing this under Mate, and trying your complaint, I find:
* window maximised: one can do nothing by hovering the screen borders. And the 'resize' right-click option is greyed. Worse - reducing the window with the top-right 'unmaximise' icon puts it minimised on the taskbar, and activating it from there puts it back full-screen! But there is an 'unmaximise' menu option which works as expected.
* normal window pushed to top: no top re-size icon on hovering.
* normal window pushed to bottom: bottom margin re-size available on hovering.
* normal window pushed to right or left screen edge: equivalent window edge resize arrow half appears, & works

I will try all these things on Plasma... So far, not proven.

CC: (none) => lewyssmith

The "grab" area is just outside the window geometry. Maximized was referenced only to say that is not part of the issue:
     - move the window if not maximized
     - if maximized, restore and likely still have to move the window
So, when the window edge aligns with the screen edge, the hot zone is outside the screen area and not available.

Maybe this was not clear enough, or I should have avoided mentioning anything about maximized...  Let me try a graphic representation:

Using left screen edge as representative for left, bottom & right... 

Window not quite at edge:
        ||
        <o>   Cursor changes to 'grab'||
        ||

Window at edge:
        |
        |\    Cursor can't reach grab's "hot" area
        |

Greatly expanded:
                  | grab  |<== window edge    
    screen edge==>| area  |   window almost at edge
                  | ~10px |
                  |  <o>  |  <== cursor changes from \ to <o>
                  |     <=|=== grab area within which cursor changes
                  |       |
    screen edge==>|<== window edge 
          | grab  |   
          | area  |   window AT edge
          | ~10px |
          |     <=|=== grab area within which cursor can't go

Also, when trying to hit the grab area, user has to consciously move cursor *outside* the window boundaries which is non-intuitive.

The "hot" zone should straddle/be centered over the window edge:
screen edge==>|<== window edge 
          | gr|ab |   
          | ar|ea |   window AT edge
          |~10|px |
          |   |   |
Now, the hot zone is available and intuitive.

HTH

I didn't test under any other DE than Plasma, but this a completely normal Plasma behaviour. If you push a window to the complete edge of a screen you can't grab the window border anymore (except for the upper one). I can't remember if it was ever this way, but normaly i dont grab the window border when it is on a screen edge. Seems like a really rare user case.


And as mentioned, it's normal for Plasma. I testet this on following OS:

Mageia 8: Plasma 5.20.4
Opensuse Tumbleweed: Plasma 5.24.2
Fedora 35: Plasma 5.24.2


So if you don't like it: raise an upstream request at KDE.

Status: NEW => UPSTREAM

But this won't be changed upstream because Plasma has powerfull gimmicks (which you can configure in systemsettings5) when you move your mouse to screen edges/corners. You can trigger different actions when you move your mouse to the edges/corners. This functionality would probably clash with window edge grabbing.

Seems to me that screen edges don't need any width -- just reaching them should be their trigger, so no clash.  I hate live screen edges, so all disabled here. Maybe I could enable them with a long delay...  Nah... still don't have a reason for using them... :)
I see you set Status to upstream; does that mean bugzilla can push reports up? Or just a flag and manual report is required?

YOU have to open a bugreport at KDE bugzilla.

We at Mageia can't change anything at this behaviour until KDE decides to change anything. Thats why i marked this bug as UPSTREAM. Normaly we should close this bug here as WONTFIX or INVALID. But i let this decission to others...

Trying this now under Plasma, I find  for an unmaximised window:
* At top screen edge: the resize handle (1/2) is there & works.
* At left, right screen edges: no resize handles.
* Against bottom taskbar: no resize handle.

But one's instinctive & immediate behaviour in such cases is to drag the window with its title bar, which is always possible (except upwards). All this is just normal window manipulation, which as we see can vary slightly according to desktop or window manager. Such is life.

This bug is such an academic obscurity, with no practical limitations, that I am changing it to Invalid. It works how it works.
I agree with sturmvogel about raising a 'bug' upstream chez KDE, and good luck. Your neat diagram in comment 4 is worth posting there.

Resolution: (none) => INVALID
Status: UPSTREAM => RESOLVED

Reported upstream and confirmed.
https://bugs.kde.org/show_bug.cgi?id=451853