[Lazarus] LCL MouseMove event problem on QT/Linux

[Paul Michell]

I have been working on my first triple platform application 
(Windows/Linux/OS X).  The user interface is very simple and so far I 
have had success in getting the source code to compile across all three 
without issue.

One part of the main form will have a simple map drawn using TCanvas 
based graphics.  I want to make the map respond to dragging with the 
mouse and on Windows I have always implemented this type of thing using 
MouseMove events.  This works as expected on Windows and OS X, but all 
mousemove event calls cease on Linux whilst the mouse button is pressed?

I have attached a simple application that demonstrates this behaviour.  
There is a mouse move event function that changes the form's caption to 
the event coordinates.  It detects the mouse left click shift state and 
swaps to showing the panning deltas whilst the button is held down.  On 
my Linux development system (Kubuntu 15..04 64 Lazarus 1.5 r49683M FPC 
3.1.1 x86_64-linux-qt) the messages stop whilst the mouse button is 
down.  On Windows and Mac it works as intended?  Is this a bug in the 
LCL QT widgetset, or am I missing something?

Thank you,

Paul Michell

-------------- next part --------------
A non-text attachment was scrubbed...
Name: MouseMove Test.zip
Type: application/x-zip-compressed
Size: 129672 bytes
Desc: not available
URL: <http://lists.lazarus-ide.org/pipermail/lazarus/attachments/20150817/b83f6752/attachment-0002.bin>