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

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Hi,
?
your demo works well here. Manjaro Linux. Lazarus 1.5 r49677M FPC 3.1.1 x86_64-linux-qt. ?
V.
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Od: Paul Michell Komu: Datum: 17.08.2015 12:18 P?edm?t: [Lazarus] LCL MouseMove event problem on QT/Linux

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Thanks for testing. I have also just tried it in an Ubuntu 13.04 Virtual Box and it works fine there built for GTK2. I'll have to test it on another QT based system.