Introduce a PlatformStyle to handle platform-specific customization of
the UI.
This replaces 'scicon', as well as #ifdefs to determine whether to place
icons on buttons.
The selected PlatformStyle defaults to the platform that the application
was compiled on, but can be overridden from the command line with
`-uiplatform=<x>`.
Also fixes the warning from #6328.
QT_NO_KEYWORDS prevents Qt from defining the `foreach`, `signals`,
`slots` and `emit` macros.
Avoid overlap between Qt macros and boost - for example #undef hackiness
in #6421.
Re-submitting this pull request with a single commit.
This patch introduces a GUIUtil class that is used when setting up the 2 tables we have so far on the Qt-GUI.
In the past you could only resize the last column, which has BTC amounts from the right border of the column header, something that was rather unnatural.
If a new table were ever to be added to the interface, fixing the last columns resizing behavior is rather simple. Just look at how we initialize here a TableViewLastColumnResizingFixer object when setting up the table header's behavior, and then how we override the resize event of the component (can be the table, or the dialog) and we invoke columnResizingFixer->stretchColumnWidth(columnIndex);
Use misc methods of avoiding unnecesary header includes.
Replace int typedefs with int##_t from stdint.h.
Replace PRI64[xdu] with PRI[xdu]64 from inttypes.h.
Normalize QT_VERSION ifs where possible.
Resolve some indirect dependencies as direct ones.
Remove extern declarations from .cpp files.
- try to enforce the same style to all Qt related files
- remove unneeded includes from the files
- add missing Q_OBJECT, QT_BEGIN_NAMESPACE / QT_END_NAMESPACE
- prepares for a pull-req to include Qt5 compatibility
