Win32 TBBUTTON fsStyle values do not fit?-CodePudding

TBBUTTON has the following structure:

typedef struct _TBBUTTON {
    int iBitmap;
    int idCommand;
    BYTE fsState;
    BYTE fsStyle;
#ifdef _WIN64
    BYTE bReserved[6];          // padding for alignment
#elif defined(_WIN32)
    BYTE bReserved[2];          // padding for alignment
#endif
    DWORD_PTR dwData;
    INT_PTR iString;
} TBBUTTON, NEAR* PTBBUTTON, *LPTBBUTTON;
typedef const TBBUTTON *LPCTBBUTTON;

Now if you see, fsStyle is a BYTE (range 0-255); however, the values you can pass are:

#define TBSTYLE_TOOLTIPS        0x0100
#define TBSTYLE_WRAPABLE        0x0200
#define TBSTYLE_ALTDRAG         0x0400
#define TBSTYLE_FLAT            0x0800
#define TBSTYLE_LIST            0x1000
#define TBSTYLE_CUSTOMERASE     0x2000
#define TBSTYLE_REGISTERDROP    0x4000
#define TBSTYLE_TRANSPARENT     0x8000

None of these can fit into a BYTE; and, quite correctly, the compiler gives a warning (warning C4305: '=': truncation from 'int' to 'BYTE') when using for example:

TBBUTTON button;
button.fsStyle = TBSTYLE_TOOLTIPS;

MSDN does not mention anything about this, so what am I missing here?

CodePudding user response：

The 'style flag' constants you have listed (TBSTYLE_TOOLTIPS thru TBSTYLE_TRANSPARENT) are window styles for a toolbar itself, not for any buttons it contains.

In the MSDN document you linked, the sentence, "A toolbar button can have a combination of the following styles.", comes after the list of those styles and refers to the list/box with the BTNS_AUTOSIZE thru TBSTYLE_SEP styles, which have values in the range 0x0000 thru 0x0080 – and these do fit in the fsStyle (BYTE) field of the TBBUTTON structure.

Here's the section of the "CommCtrl.h" header that defines these:

#define BTNS_BUTTON     TBSTYLE_BUTTON      // 0x0000
#define BTNS_SEP        TBSTYLE_SEP         // 0x0001
#define BTNS_CHECK      TBSTYLE_CHECK       // 0x0002
#define BTNS_GROUP      TBSTYLE_GROUP       // 0x0004
#define BTNS_CHECKGROUP TBSTYLE_CHECKGROUP  // (TBSTYLE_GROUP | TBSTYLE_CHECK)
#define BTNS_DROPDOWN   TBSTYLE_DROPDOWN    // 0x0008
#define BTNS_AUTOSIZE   TBSTYLE_AUTOSIZE    // 0x0010; automatically calculate the cx of the button
#define BTNS_NOPREFIX   TBSTYLE_NOPREFIX    // 0x0020; this button should not have accel prefix
#define BTNS_SHOWTEXT   0x0040              // ignored unless TBSTYLE_EX_MIXEDBUTTONS is set
#define BTNS_WHOLEDROPDOWN  0x0080          // draw drop-down arrow, but without split arrow section