Currently using KDE4, If I insert a USB stick:
1. I get a popup window showing me the available devices with possible actions.
2. The window is resizable.
3. If I select one of the available actions ie "Open with File Manager", Dolphin will open showing the currrent contents of the device.

Currently using KDE5, If I insert a USB stick:
1. I only get an icon on the task bar and I must select the icon to get a popup window with the possible actions.
2. The window isn't resizable.
3. If I select one of the available actions ie "Open with File Manager", I get a message "unable to mount device". So I figured out the following:
A. Select the check mark on the right side to mount the device.
B. Select the available action ie "Open with File Manager" to open Dolphin.

How can I get KDE5 to act like KDE4?
Thanks

Gentoo ~amd64
KDE Apps 15.04.3
KDE Frameworks 5.11.0
KDE Plasma 5 5.3.2
CI7-4770 and CI7-4790
4600 HD
8 GB ram

KWin Support Information:
The following information should be used when requesting support on e.g. http://forum.kde.org.
It provides information about the currently running instance, which options are used,
what OpenGL driver and which effects are running.
Please post the information provided underneath this introductory text to a paste bin service
like http://paste.kde.org instead of pasting into support threads.

==========================

Version
=======
KWin version: 5.3.2
Qt Version: 5.4.2
Qt compile version: 5.4.2
XCB compile version: 1.11

Operation Mode: X11 only

Build Options
=============
KWIN_BUILD_DECORATIONS: yes
KWIN_BUILD_TABBOX: yes
KWIN_BUILD_ACTIVITIES: yes
HAVE_WAYLAND: no
HAVE_WAYLAND_EGL: no
HAVE_WAYLAND_CURSOR: no
HAVE_XKB: no
HAVE_INPUT: no
HAVE_XCB_CURSOR: yes
HAVE_XCB_SYNC: yes
HAVE_X11_XCB: no

X11
===
Vendor: The X.Org Foundation
Vendor Release: 11701000
Protocol Version/Revision: 11/0
SHAPE: yes; Version: 0x11
RANDR: yes; Version: 0x14
DAMAGE: yes; Version: 0x11
Composite: yes; Version: 0x4
RENDER: yes; Version: 0xb
XFIXES: yes; Version: 0x50
SYNC: yes; Version: 0x31
GLX: yes; Version: 0x0

Decoration
==========
Plugin: org.kde.breeze
Theme:
Blur: 0
onAllDesktopsAvailable: true
alphaChannelSupported: true
closeOnDoubleClickOnMenu: false
decorationButtonsLeft: 0, 2
decorationButtonsRight: 6, 3, 4, 5
borderSize: 3
gridUnit: 16
font: DejaVu Sans,11,-1,5,75,0,0,0,0,0
smallSpacing: 4
largeSpacing: 16

Options
=======
focusPolicy: 0
nextFocusPrefersMouse: false
clickRaise: true
autoRaise: false
autoRaiseInterval: 0
delayFocusInterval: 0
shadeHover: false
shadeHoverInterval: 250
separateScreenFocus: false
placement: 4
focusPolicyIsReasonable: true
borderSnapZone: 10
windowSnapZone: 10
centerSnapZone: 0
snapOnlyWhenOverlapping: false
rollOverDesktops: false
focusStealingPreventionLevel: 1
legacyFullscreenSupport: false
operationTitlebarDblClick: 5000
operationMaxButtonLeftClick: 5000
operationMaxButtonMiddleClick: 5015
operationMaxButtonRightClick: 5014
commandActiveTitlebar1: 0
commandActiveTitlebar2: 30
commandActiveTitlebar3: 2
commandInactiveTitlebar1: 4
commandInactiveTitlebar2: 30
commandInactiveTitlebar3: 2
commandWindow1: 7
commandWindow2: 8
commandWindow3: 8
commandWindowWheel: 31
commandAll1: 10
commandAll2: 3
commandAll3: 14
keyCmdAllModKey: 16777251
showGeometryTip: false
condensedTitle: false
electricBorderMaximize: true
electricBorderTiling: false
electricBorderCornerRatio: 0.25
borderlessMaximizedWindows: false
killPingTimeout: 5000
hideUtilityWindowsForInactive: true
inactiveTabsSkipTaskbar: false
autogroupSimilarWindows: false
autogroupInForeground: true
compositingMode: 1
useCompositing: true
compositingInitialized: true
hiddenPreviews: 1
unredirectFullscreen: false
glSmoothScale: 2
colorCorrected: false
xrenderSmoothScale: false
maxFpsInterval: 16666666
refreshRate: 0
vBlankTime: 6000000
glStrictBinding: true
glStrictBindingFollowsDriver: true
glCoreProfile: true
glPreferBufferSwap: 112
glPlatformInterface: 1

Screen Edges
============
desktopSwitching: false
desktopSwitchingMovingClients: false
cursorPushBackDistance: 1x1
timeThreshold: 0
reActivateThreshold: 1050
actionTopLeft: 0
actionTop: 0
actionTopRight: 0
actionRight: 0
actionBottomRight: 2
actionBottom: 0
actionBottomLeft: 0
actionLeft: 0

Screens
=======
Multi-Head: no
Active screen follows mouse: no
Number of Screens: 1
Screen 0 Geometry: 0,0,1920x1080

Compositing
===========
Compositing is active
Compositing Type: OpenGL
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Haswell Desktop
OpenGL version string: 3.3 (Core Profile) Mesa 10.6.1
OpenGL platform interface: GLX
OpenGL shading language version string: 3.30
Driver: Intel
GPU class: Haswell
OpenGL version: 3.3
GLSL version: 3.30
Mesa version: 10.6.1
X server version: 1.17.1
Linux kernel version: 4.1.1
Direct rendering: Requires strict binding: yes
GLSL shaders: yes
Texture NPOT support: yes
Virtual Machine: no
OpenGL 2 Shaders are used
Painting blocks for vertical retrace: no

Loaded Effects:
---------------
zoom
slidingpopups
kwin4_effect_login
screenshot
kwin4_effect_windowaperture
minimizeanimation
kwin4_effect_translucency
desktopgrid
kwin4_effect_fade
kwin4_effect_maximize
kwin4_effect_dialogparent
highlightwindow
blur
contrast
logout
dashboard
startupfeedback
kscreen

Currently Active Effects:
-------------------------
blur
contrast

Effect Settings:
----------------
zoom:
zoomFactor: 1.2
mousePointer: 0
mouseTracking: 0
enableFocusTracking: false
followFocus: true
focusDelay: 350
moveFactor: 20
targetZoom: 1

slidingpopups:
fadeInTime: 150
fadeOutTime: 250

kwin4_effect_login:

screenshot:

kwin4_effect_windowaperture:

minimizeanimation:

kwin4_effect_translucency:

desktopgrid:
zoomDuration: 300
border: 0
desktopNameAlignment: 0
layoutMode: 0
customLayoutRows: 2
usePresentWindows: false

kwin4_effect_fade:

kwin4_effect_maximize:

kwin4_effect_dialogparent:

highlightwindow:

blur:
blurRadius: 12
cacheTexture: true

contrast:

logout:
useBlur: true

dashboard:
brightness: 0.5
saturation: 0.5
blur: false

startupfeedback:
type: 0

kscreen:

This has nothing to do with kwin - that window is either set to have a fixed size or is bypassing the WM entirely.

The described behavior is either deliberate or simply a bug in the plasmoid.

luebking wrote:This has nothing to do with kwin - that window is either set to have a fixed size or is bypassing the WM entirely.

The described behavior is either deliberate or simply a bug in the plasmoid.

How do I check whether it is a bug or not?

Report one (http://bugs.kde.org, plasmashell, "Device Notifier")
If the maintainer says "intended, because..." it's not a bug

I submitted a buy report...
https://bugs.kde.org/show_bug.cgi?id=350060

There has been no reply to the bug filed on this topic.

Sorry to hear.
Unfortunately, it's entirely not my territory - I don't even know whom to blame

This issue continues without any response to the bug so I'm closing the thread "Unresolved"
Current KDE info:
Plasma 5.6.1
Frameworks 5.20
KDE Apps 15.12.3